Xin Zhao Build
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Alright, this is my first build, so go easy please. If you take issue with what I've chosen, explain why and I'll test that out. Xin is almost my only hero I play (Vladimir and Master Yi on occasion), so I like to think I have an idea as to what I'm doing.
So, what this build shoots for is a mix between Attack Speed and Attack Damage (with some lifesteal to suppliment Xin's natural regeneration from his passive.) The Dorans's shield can be replaced at the endgame with whatever is situation appropriate.
For the kill, Use your Audacious Charge on the squishiest/highest threat target in the group you're attacking, and then Crescent Sweep (if it's up). From there, pop Battle Cry and almost instantaneously pop your Three Talon Strike as well. Follow, and if they don't die during this, by this point your charge should be up again, so wash, rinse, and repeat. Remember, Xin isn't the tankiest hero around, so after you get a kill, you want to back out of the middle of the fight in order to make yourself less of a target. Personally I run back to the casters, and charge back in on a second target if I have the stamina. Also remember Xin is a high priority target himself, don't be afraid to back off if the need arises.
As for laning, feel free to harass. Don't use your charge unless you're certain you can get away or get the kill. However at 1, with Three Talon Strike, you will be able to hide in "their" grass, and as the enemy champion approaches, pop Three Talon and you'll be able to do a significant amount of damage. If your partner has a similar early game trick, it is completely feasible to get a pre-minion kill in this fashion.
Clarity was chosen for increased time in lane (and let's face it. Everyone loves free mana!), and Teleport was chosen to get the powerhouse into a team fight ASAP.