I have been testing set-ups for Xin for about a month now, and this is the best one I have used to get good, consistent results with.

You might think I'm crazy for going all out on attack speed with the Runes. The thing is, it works. A maxed out speed rune page gives you a 38% attack speed boost. After you get the Berserker Greaves, your attack speed is already 1.2.

I decided to go 21/0/9 on the masteries. Offense obviously for the damage, speed, and crit damage buffs. In support I chose raised regen, exp, and gold earning just to help out in-lane.

In the Items as well as in the runes, the focus is speed. I have tested getting the Greaves and then right into a Phantom's, but I have found that I am lacking in the damage department when I go to dive at someone. This is why I chose the black cleaver as my second item. It's passive goes right along with Three Talon Strike. The speed and damage boosts are also nice. After that, it's pretty straight forward build wise. Just rotate damage and speed. Phantom's, Bloodthirster, Phantom's, and then Infinity Edge to finish it off. I also found that if for some reason you finish this build (I have rarely finished this build and not had the game end shortly there-after) you could replace the Berserker Greaves with an additional Phantom Dancer.

Xin's skill sequence is quite easy. You want to lvl Talon strike first because the air-pop at the end of the three strikes is very useful in lane and you need the damage boost because of the focus of speed in the runes page and the item build. I then chose to lvl up Audacious Charge because honestly, after the 20% attack speed boost you get from the lvl 1 Battle cry, another 5% increase is not worth the skill point because you already get enough speed from the runes and items. Plus the increased slow and damage from Audacious Charge is nice. How to use these skill is to charge in with Audacious Charge, then use the Crescent Sweep to start your armor and magic resist buffs. Also it does more damage the higher the enemy's health is so you want to use it off the bat. After the Sweep, simultaneously use Three Talon Strike with Battle Cry to start the air-pop combo and the cooldown reduction.

The summoner spells for Xin are also quite the no-brainer. Exhaust to slow after the effect from your Audacious Charge has worn off, and ignite to inflict the damage to give you the upper hand in a fight.