Xin Zhao is a very offensive champ, he got alot of dmg with his Three Talon Strike, he got alot of attack speed with battle cry, slow and jump with audacious charge, then his AOE ulti Crescent sweep alot of damage. Xin Zhao should never start a team fight when the tank has started Xin Zhao use Audacious Charge, then Battle cry, three talon strike when you are in the middle of everyone use you ulti.

Boots:
Berserkers Greaves is the best for the ultimate dmg champ, but if you are against alot of magic damage, stuns and/or slows take mercury treads instead.

Core items:
Black Cleaver, Frozen Mallet and Phantom Dancer is the three core items for the perfect dmg, hp, slow, crit, attack speed and every thing there is needed for Xin Zhao.

Off items:
After buying boots, and core items you have several options, if you dont feel you damage enough you can buy bloodthirster or a black cleaver more. But if you die too much you can buy a Banshee's veil, i would always prefer a Banshee's veil if i are against; blitzcrank (rocket grab), ezreal (Trueshot barrage(ultimate)), karthus (requim(ultimate)), Ashe (Enchanted Crystal Arrow(ultimate)), coz then if i have very low hp, and i'm fleeing then banshee's veil will save me. If you are up against a champ with alot of healt like cho gath with warmog's armor, buy Madred's Bloodrazors it damage 4% of the targets hp per hit. Sterk's Fervor is also a good idea if you have alies that can use the aura.

Exhaust:
Is very good if your against someone who have alot of damage, when attacking use your exhaust after your slow from audacious charge is gone.

Ignite:
Ignite is very good to get first blood, remember first use your ignite when your target is fleeing. Remember that ignite reduces healing done too your target so if you are against dr. mundo, swain or vlademir etc. use it on them so their healing abillities are reduced.

Three Talon Strike:
Is the ultimate damage ability, it scales with more than 100% damage, and then the third attack knocks airborne. Pop it first then Battle cry will take the cooldown down and you can maybe use one more time.

Battle Cry:
Passive: gives you attack speed.
Active: Double up the attack speed and every attack reduces other cooldowns by 1 second pop first in battle then you can use your attacks again fast.

Audacious Charge:
Your jump, slow and damage attack. A very important thing to know/remember is that Audacious Charge slows in a little AOE so if you are hunting someone down and minions are close use it on the nearest minion then it slows the champion also and you can hunt them down and kill them.

Crescent Sweep:
Damage alot in AOE, the more hp your enimies have the more it damages, so use it first in the fight, also it grants you extra armor and magic resistance.

Earlygame:
Start taking Audacious Charge, and if you want firstblood, get at teamate with stun or taunt like anivia, rammus or blitzcrank. If you are against a heavy damage and a more week one like garren and karma, start out attacking karma use everything exept exhaust on karma, the exhaust garren, so he wont damage you that much, get the kill and run from garren, then you can lane on. If you can't get firstblood just lane stay passive and last hit minions, dont use too many abilities bacause you dont have very much mana. As soon you have B.F. Sword try to get a kill that early with B.F. Sword your Three Talon Strike damage sick.

Midgame:
Midgame is all about get minions push towers and gain levels. Kills is of cause very important but don't hunt them to much, if you dont have mana, or your cooldowns are up dont go after a kill. In this periode it's very important too remember still last hit minions for the money, many often forget it here.

Lategame:
Lategame is all about pushing towers, and get kills, your are very good late game, but care not to die too much Xin Zhao is not unkillable. Start fights with, E - W - Q - R, right after each other that is the perfect chain.

My rune page is very overall, u can use it for almost every champion.

Quintessence:
Health, Flat health is very good in the beginning makes you less killable, and gives you the control in the start if you have the opper hand, you have it more easy to push and get firstblood.

Seals:
Dogde, Flat dogde is very good in the whole game special in the beginning, if you have good dogde you are less killable.

Glyph:
Cooldown reduction, flat or per level is your own choice i prefer flat because there is not the big diffrence between it. If you are in combat and start with your audacious charge then if the other flees you can use audacios charge again short time after the first time.

Marks:
Armor penetration, flat armor penetration is very good so you make more damage, you can use it against all champs because every champ have a base armor.