Here's a few house rules, mechanics changes and revisions I use to make my Kindred of the East games run smoothly. Hopefully you'll find something in all this worth using.
I use Vampire Revised, and a lot of the rules here are designed to bring KotE in line with Revised rules. However, I've put my own spin on some things, particularly soak and rolls for invoking soul states. I like KotE (obviously), but one of its drawbacks is complexity; the number of die rolls one has to make in an average game is truly daunting. The poor editing and organization of the core KotE book, sparse index, and contradictory rules make running the game difficult at times. (Obviously, I still love the game, however.) So I've taken it upon myself to simplify and streamline the system. To this end I've eliminated resisted rolls where I can.
Some Revised-compatible rules changes, as well as general KotE errata, were printed in the Kindred of the East Companion and the Vampire Storyteller's Handbook. If any of the rules changes below look familiar, it's because I use some of those rules or were inspired by them, or came to some of the same conclusions as the writers did. In some cases, however, I don't use those rules (or the rules as written in the KotE books), discarding them in favor of my own. I'm not trying to take credit for anyone else's work, but I want all my KotE rules changes to be easily accessible here, rather than me or my players having to reference two or three different books to figure out how Black Wind (or whatever) works. Plus, for those of you who can't afford to blow close to $50 (or more, now that those books are no longer being printed) for two extra books to make KotE work, you can now visit my website, free of charge... though the two books mentioned are worthy of purchase in their own right, if you can find them.
Note: When writing the Disciplines, rites, Merits and Flaws, etc., elsewhere on this page, I didn't incorporate any of my house rules into them; I want my material to be accessible to everyone. When using my supplemental material, you may use these rule changes or not, as you like.

The Measure of a Demon
I offer a simple method for generating Kindred of the East characters that avoids all the trait minimum stuff. I increased the freebie point cost for Willpower to 2 per dot, to balance the fact that they start with a base rating of 5; exp cost to raise Willpower is still current x 1.
Attributes: 15 points to spread as you like, but no more than 8 can be devoted to any one category. Characters start with the first "free" dot in every Attribute, of course.
Abilities: 30 points to spread, but no more than 3 dots can be invested in any one Ability with initial spread.
Backgrounds: 5 points. Backgrounds cost one Background/freebie point per dot up to three; every dot beyond the third costs two points. (So a Background of 4 dots costs a total of five Background/freebie points, and a rating of 5 cost seven points.)
For every dot in the Rites Background, a character gains two levels of rites. (So Rites 3 means the character starts out with six levels of rites.)
Advantages: 3 dots of Disciplines (one Demon Art, two others); 5 dots to spend on the four Virtues (characters begin with one dot in Yin, Yang and Hun, and three dots in P'o).
Step Five: Finishing Touches. Record Willpower (5); determine beginning Chi (halve each Chi Virtue, round up; the result is one point of Chi of the corresponding type); record Dharma (1).
Step Six: Spend freebie points (15). Willpower may be no higher than 8 at start of game, and no Discipline may exceed three dots at this time.
Merits and Flaws: I set a maximum of 7 points' worth of Flaws. (Be sure to check with me before selecting Merits and Flaws, because some I don't allow: for example, Dark Fate, and those like Overconfident and Enchanting Voice that can be simulated through roleplaying or via taking standard traits.) A wide selection of Merits and Flaws may be found here .

Gameplay
The system White Wolf uses for the World of Darkness functions really well for most things, but it runs a little clunky in combat. While the system itself is sound, it runs slowly with initiative rolls, attack rolls, damage rolls, and soak rolls. While some of this is unavoidable, I feel we should try to minimize dice rolling whenever possible. Drawing from a variety of sources (including the nWoD system), I've eliminated rerolls and streamlined initiative.
Die Rolls: In my games, natural results of 10 on all die rolls except damage counts as two successes, except when the difficulty is 10; in this case, each 10 is one success. This isn't over-the-top, in my opinion, as the law of averages means 1s will come up as often as 10s.
1s on damage rolls are simple failures, and don't reduce damage successes. 10s on damage rolls are simple successes, and don't count as two damage successes.
Specialties: While conceptually much the same, I do specialties differently than in the book. Specialties cost two freebie points/ three exp, or one Ability dot from your inititial spread at character generation; specialties only apply to Abilities, and not Attributes. A character can have a specialty in any Ability he has, regardless of rating, and can have as many specialties as he has dots in that trait. So someone with a Occult 2 of can have up to two Occult specialties.
A specialty allows you to roll an extra die when taking actions or making rolls involving that specialty. For example, a character with Occult 2 and the Ghost specialty adds three dice to his rolls when dealing with the Restless Dead, but not when attempting to understand any other supernatural phenomena.
Initiative: Initiative is now determined by summing the character's Dexterity and Wits, and adding the result of 1d10. This result is kept for the rest of the combat; initiative isn't rerolled at the beginning of each turn. However, increases to Dexterity and initiative bonuses provided by the Demon form or Dragon Dance (Yang Prana ●●● will increase initiative appropriately, on the turns they are used. The Storyteller counts down from the highest total, allowing characters to act on their initiative results each pass. For example, a character with Dexterity 2 and Wits 3 enters combat. She rolls a 4 on her initiative die, which means she goes on an initiative count of 9 (2 + 3 + 4).
A character may elect to sacrifice her action for the turn to add 3 to her initiative result for the next turn, and for the rest of the fight. Those with extra actions provided through Dragon Dance may sacrifice one of those actions to gain this bonus next turn, and still act that turn; otherwise, a player must sacrifice her action for that turn (and may not take multiple actions). Reflexive actions may be taken during "skipped" turns, such as yelling a short warning or healing with Chi.
Any Discipline effect that gives bonus initiative dice (such as Yang Prana) instead adds points to the Dexterity + Wits + 1d10 initiative roll. So, three extra dice instead adds a +3 bonus to the roll.
Damage: Pay attention, this is a little involved.
Now there are three types of damage: bashing, lethal and aggravated, with the "normal" damage of previous editions is now separated into the bashing and lethal categories (though shots to the head do inflict lethal). Bashing damage covers those forms of damage that may impair vampires, but that don't cause actual grievous wounds: kicks, punches, poisons, falls and firearms. As with Kin-jin, bashing damage is halved after soak for all Cathayans, with fractions rounded down. Lethal damage is more dangerous than bashing damage, and inflicted by swords, knives, and certain particularly nasty Martial Arts attacks. This sort of damage is soaked normally.
As a rule of thumb, damage values from "Second Edition" KotE are reduced by one die, while Revised-era damage ratings in the book remain the same. For example, the Demon Shintai characteristic: Claws inflicts Str +1 aggravated damage.
According to Revised rules, vampires making Brawl, Martial Arts or Melee attacks may add an extra die of damage for each success beyond what is needed to hit a target (like Firearm attacks). This includes any attack that has a "to-hit" roll and rely on accuracy, such as Yang Mantle (Yang Prana ●●) and Yin Mantle (Yin Prana ●●) attacks. However, this doesn't apply to area-effects like Goblin Scorch (Ghost-Flame Shintai ●●●●) or Five Poison Cloud (Bone Shintai ●●●●).
Unlocking Demon Chi: To unlock "raw" Demon Chi, the vampire must roll P'o (difficulty Hun +3) (this is a reflexive action); a successful roll grants the character access to his Demon Chi for that scene. However, four or more successes on this roll sends the vampire into Fire Soul. Raw Demon Chi may now be spent to gain extra actions, speed or damage successes, as described in the KotE core rulebook. A vampire can spend a number of Demon Chi per turn up to his Stamina rating; however, this may invoke Fire Soul if the expenditure exceeds the vampire's Dharmic limits on spending Chi (see Spending Chi, below). Any benefits gained from spending Demon Chi are gained the turn after it is spent. In addition, on any turn the vampire spends raw Demon Chi, Yin roll difficulties to avoid entering Fire Soul are at +2.
Vampires that spend Demon Chi for Discipline effects (such as when using Demon Arts) don't have to roll to unlock Demon Chi; this only applies to vampires using Demon Chi in its "raw" form.
Spending Chi: Normally, a character can only spend one type of Chi per turn (Yin, Yang or Demon); however, those with the Equilibrium Discipline can spend both Yin Chi and Yang Chi in the same turn (assuming their Dharma scores allow them to spend multiple Chi). The amount of Chi a character can spend per turn is determined by her Dharma rating (see Dharma chart, pg. 54). However, Demon Chi can never be spent in the same turn that Yin Chi or Yang Chi is spent.
Demon Chi follows different rules. A character can spend a number of Demon Chi per turn equal to her Stamina; however, exceeding her normal Dharmic limit forces an immediate roll to avoid Fire Soul (if a Yin roll to avoid Fire Soul is already being made that turn, make a single roll but increase the difficulty by 2). For example, a disciple (Dharma rating 2) with a Stamina of 3 can blow up to three demon Chi per turn, but since he is normally limited to spending 1 Chi per turn (according to his Dharma rating), he must roll to avoid Fire Soul if he spends more than one Demon Chi per turn. Only demons of proper enlightenment can channel their Hell-powers without it overwhelming them.
Many Discipline effects call for the expenditure of multiple Chi. This might lead one to believe that a character who can't spend that amount of Chi per turn can't use such a power. This is not the case. The character simply spends Chi over successive turns; on the turn that the vampire meets the power's cost, the power takes effect. For example, a jina (Dharma rating 4 or 5) wants to use Goblin Lantern (Ghost-Flame Shintai ●●●●●), which costs 3 Chi. She may spend two Chi the first turn and one the second turn, or spend one Chi over three turns, or whatever.
Spending Chi is a reflexive action.
Little Death (and Final Death): Kuei-jin who lose all their health levels with no Chi in their bodies don't meet Final Death; they reanimate their corpses after a number of nights equal to their permanent Yin, but wake up ravenous -- automatic Fire Soul until at least two points of Chi are eaten. However, aggravated damage kills Kuei-jin permanently (as is the case with everyone). In most cases, meeting Little Death isn't an Act of Blindness (and thus the Kuei-jin doesn't risk losing Dharma), unless the Kuei-jin achieved that state through an extraordinary act of stupidity: For example, striking an elder, or jumping onto a moving train from a helicopter.
Using the P'o to Resist Mental Domination: A Kuei-jin can't use the P'o to resist Dementation or any power (Gift, Arcanoi, Sphere effect, et cetera ad nauseum) that causes insanity or causes spiritual corruption. The P'o revels in madness and wickedness, and has no reason to fight urges that may inspire an Act of Blindness...
Using one's P'o to shake off the effects of mental influence is a reflexive action.
Dharmic Social Roll Bonuses: As those of superior enlightenment are harder to impress than those of more limited understanding, subtract the number of bonus dice the Kuei-jin gains when interacting with those of lower Dharma from other vampires' bonus dice. (See KotE core book, pg. 54.) For example, while a Dharma 8 ancestor adds three dice to his social dice pools when interacting with disciples and jina, he only adds one die to his pools when attempting to sway a Dharma 7 mandarin.
While Dharmic social rolls bonuses apply to Kindred, those Kin-jin of great age and/or strong blood are less easily cowed. Use the age of the Kindred or his Generation, whichever is most favorable, when determining an elder Kuei-jin's social roll bonuses against her; when using age, compare the actual age of the vampire to the minimum age required to achieve a Dharma level (see Dharma chart). For instance, a Dharma 8 Kuei-jin squaring off with a Kindred 500 years old and/or that is 5th Generation gains no social roll bonuses against her.

Soul States
I understand the wisdom of using the resisted roll mechanic for simulating characters struggling against their Demons. However, in application, this means that an awful lot of resisted rolls are made in a typical game session. Therefore, I've turned the rolls to resist [whatever] Soul into a standard roll, where the player rolls once against a standard difficulty. This speeds things along greatly.
(I still use resisted rolls for Dharma rolls, however. These rolls don't occur often enough to slow down the game, and I feel that Dharmic advancement is too important to hinge on a single die roll.)
The vampire may make one Virtue roll to resist a change in soul states each turn (as described below). She must accumulate three or more successes to maintain Wind Soul; this is often an extended roll, and as long as she accumulates at least one success on her Virtue roll each turn, she may continue to roll. However, on the turns the character is struggling with her P'o, she finds it difficult to focus and can't spend Willpower except to gain successes on the Virtue roll. If the character fails a Virtue roll before she accumulates the requisite three successes, the Kuei-jin enters Fire, Wave or Shadow Soul (as appropriate). Rolling to avoid a change in soul states is a reflexive action.
Roll to Resist Fire Soul (Frenzy): The character's player rolls Yin, base difficulty equal to [P'o +3] (maximum difficulty 9); subtract the Kuei-jin's Social roll bonus (see Dharma chart, pg. 54) from the difficulty of this roll, as exceptionally enlightened monsters find it easier to resist the baser urges of their Demons. This is the "default" difficulty for the character's rolls to resist Fire Soul, and may be modified by circumstances. (For example, a Devil-Tiger is far more likely to fly off the handle when bitten by a Goblin Spider than when insulted by some impudent Running Monkey.)
Roll to Resist Wave Soul (Rotschreck): Roll Yang, base difficulty equal to [P'o +3] (maximum difficulty 9); subtract the Kuei-jin's Social roll bonus (see Dharma chart, pg. 54) from the difficulty of this roll. The Storyteller is free to adjust this base difficulty based on the situation, as not everything will inspire panic to the same degree.
Roll to Resist Shadow Soul: The character's player rolls Hun, difficulty [P'o +3] (maximum difficulty 9). One with advanced understanding of her nature can more easily resist the pull of her P'o (as she has learned to better assimilate her Demon); subtract the character's Social roll bonus from the difficulty of this roll.
This roll is made whenever the character must resist Shadow Soul, including when she activates Demon Arts (see below).

Disciplines
While Kuei-jin Disciplines tend to be more flexible and powerful than those of Kindred, I feel that the mechanics for some Disciplines are unnecessarily harsh and complicated. I think the fact that Cathayan Disciplines cost 10 Freebie per dot and cost rating x 8 to raise is enough of a balancing factor in many cases.
Beast Shintai: Click the link to see my revision of this Discipline.

Black Wind: Having to make a P'o roll every turn the Discipline is in use is unnecessary, in my opinion; while Black Wind is cool, it isn't that powerful. A character must roll to avoid both Shadow Soul and Fire Soul the first turn it is used; after that (whether the Kuei-jin managed to maintain Wind Soul or not), he can continue using Black Wind for as long as he wants. While he need not roll every turn to avoid entering Fire Soul, Yin roll difficulties to avoid entering Fire Soul are at +1 while Black Wind is in effect; the difficulty modifier for a Kuei-jin using both Black Wind and Demon Shintai is +2.
Combining Black Wind with Yang Prana's Dragon Dance is especially risky, forcing the character's player to achieve at least one success on a Yin roll (difficulty 8) each turn the Disciplines are combined to avoid Fire Soul.
Unlike extra actions gained from Celerity, spending raw Demon Chi, or other Discipline effects like Dragon Dance, a Kuei-jin using Black Wind gains extra actions on the turn he spends the Demon Chi for them, making the first dot of this Discipline quite worthwhile.
Chu'iu Muh (Dragon Tears): A vampire can't use the P'o powers of Dragon Tears while in his "normal" (human) form unless he is in Shadow Soul, in which case he may not use the Discipline's Hun powers. Likewise, a character in Demon Shintai form may only use the P'o powers of Dragon Tears, and can't use the Hun powers.
Demon Shintai: The character must resist Shadow Soul when first activating this Discipline. There is no practical time limit for this Discipline; the character may assume Demon form upon awakening and maintain it until sunrise, if she wants. Keep in mind, however, that all rolls to avoid Shadow Soul, Fire Soul and Wave Soul are at +1 difficulty while in Demon form, (and that difficulties to resist Fire Soul while combining this Discipline with Black Wind are +2).
A character may assume Demon form immediately, in emergencies, by blowing three Demon Chi at one time (she may do so even if her Stamina is lower than 3). However, this automatically sends her into Shadow Soul for several hours (no roll is allowed to resist).
Flesh Shintai: Unless the vampire uses The Ten Thousand Forms (●●●●●) to assume a form that can inflict lethal or aggravated damage, all damage inflicted by use of this Discipline (including bashes using detached limbs, constriction and Pelasits) inflict bashing damage in most cases. A vampire using Long Neck (●) to bite from afar, slicing with a sword held by a detached arm, or striking with a detached tail that has spikes (ala Demon Shintai) may inflict aggravated or lethal damage, as appropriate.
Internalize: Those using Distant Death Kata (●●●) can only make simple physical attacks. Punches, kicks, sword swipes, and attacks with Bloodlashes (Blood Shintai ●) and weapons created through Bone Obedience (Bone Shintai ●●●) are fine for use with Distant Death Kata, but not non-damaging attacks, special attack effects (such as Martial Arts maneuvers), or Discipline effects like Goblin Face (Ghost-Flame Shintai ●), Lotus Cloud (Flesh Shintai ●●●) or the Demon Shintai characteristic: Poisoned Fangs. The character must score three or more successes on the attack roll (normal difficulty for the attack) to hit his opponent, and while extra successes beyond what's need to hit add to the damage die pool (successes -4), automatic successes gained from Black Wind or raw Demon Chi do not add to the damage. Attacks that inflict bashing or aggravated damage instead do lethal damage through Distant Death Kata (as a focused blast of Chi, rather than the weapon or attack itself, is what inflicts damage).
Iron Mountain: To use Iron Mountain, the player must spend a point of Demon Chi and roll to avoid both Shadow Soul and Fire Soul the first turn it is used; after that (whether the Kuei-jin managed to maintain Wind Soul or not), he gains the benefits of Iron Mountain for the rest of the scene.
Jade Shintai: When employing an elemental mantle though Jade Servant of the August Personage (●●●●●), the damage inflicted by the character is lethal damage unless the Scarlet Phoenix version is used, in which case the Cathayan's strikes inflict aggravated damage (and inflicts aggravated damage when struck by others). When activating Scarlet Phoenix, keep in mind that Jade Shintai doesn't grant the vampire any special protection from the effects of the fire he puts his hand in, and will suffer damage from the act unless he he has special protection (such as Iron Mountain). However, once the Scarlet Phoenix mantle is activated, the vampire gains a die with which to soak fire damage. All mantles add three dice to the user's soak pools.
Tapestry: A vampire subjected to the "bad joss" effect of Chi-Shaping (●●●) is more likely to fail, but not more likely to botch. Any 2s rolled while affected by bad joss negate successes as 1s do, but do not count as 1s for purposes of determining botches.
The ability to detect the "Chi ripples" caused by Kindred vitae isn't innate to Kuei-jin; only those intimately familiar with ambient Chi can perceive such phenomena. A Kuei-jin with Tapestry 1 can detect the current use of blood-based Kin-jin Disciplines, or the use of Blood Points to improve Physical Attributes, in a radius of [Tapestry x 3] meters. Perceiving the expenditure of Blood points requires a Perception + Occult roll, difficulty 9; if the Kuei-jin actively looks for such Chi disturbances, the difficulty is reduced to 7. (Note: the Kuei-jin must have some reason to suspect Kindred activity to look for vitae-based Chi disturbance; not even the most paranoid Cathayan is on alert for Kin-jin all the time.) If the Kuei-jin is in, or is extending his senses into, the Yin World or Yang World, reduce difficulties for sensing vitae expenditure by 1. One success on the Perception + Occult roll is enough to detect vitae phenomena in the area of effect, with additional successes yielding more information (such as the direction and magnitude of the disturbance).
Yang Prana: As stated above in initiative rules, Principle of Motion adds 3 to the Kuei-jin's initiative total per point of Yang Chi spent, not three dice.
As all extra attack successes add to damage dice pools in Revised, Dragon Dance (●●●) was updated in the Vampire Storyteller's Handbook to make the power more useful. Spend one Yang Chi to activate the power for a number of turns equal to your Yang Virtue. During this time, you are in a state of controlled Fire Soul. Opposing vampires roll against +1 difficulty to affect you with mental powers (such as Obligation, Presence, etc.). You don't suffer wound penalties, and when using Brawl or Martial Arts maneuvers, your attack and damage roll difficulties are reduced by one. Brawl and Martial Arts maneuvers that inflict bashing damage instead inflict lethal damage. One Yang Chi may be spent for each extra action (remember Dharmic limits of Chi expenditure), but those actions must be taken next turn. Finally, using Dragon Dance and Black Wind simultaneously makes the character very deadly, but the character's player must achieve at least one success on a Yin roll (difficulty 8) each turn the Disciplines' effects are combined to avoid Fire Soul.