Tireless Warrior: Xin zhao is healed for 30 points every 3 attacks that he lands. This amount increases by 5 every 2 levels.
-Life steal can be a very overpowering passive. Boosting a champions strengths is a great way to make them ravenous and unstoppable in game. Since Xin already has life steal, it is easy to make this passive into a much more vital part of his strategy with attack speed and life steal items.
Three Talon Strike:Xin Zhao prepares to unleashes a fearsome combo, causing his next 3 standard attacks to deal his attack damage +15/30/45/60/75 to enemy targets, with the final attack knocking his opponent into the air.
-Remember this can work at a stun. Therefore, enemies with charged ults, such as Nunu or Malzahar, can be knocked in the air before they finish their ability. This is one reason that this ability coupled with Battle cry creates a strategic combination.
Battle Cry:Passive: Increases Xin Zhao's attack speed by 15/20/25/30/35%
Active: Xin Zhao unleashes a battle cry, increasing his attack speed by double the passive amount for 7 seconds, and causing his standard attacks to reduce all other ability cooldowns by 1 second
Audacious Charge:Xin Zhao charges an enemy unit, dealing 70/110/150/190/230 (+40% of ability power) damage to all nearby enemies and slowing them by 40% for 2 seconds.
-It is wise to remember that fleeing enemies are slowed nearby, thus using audacious charge on a minion near a fleeing champ will cause them to be slowed and allowing Xin and teammates to catch up.
Cresent Sweep:Xin Zhao unleashes a fierce spear sweep on targets around him, dealing 150/275/400 + 25% of their current health in physical damage. His magic resistance and armor are increased by 30/40/50 for the next 8 seconds.
-Be careful not to waste (or perhaps a better word is simply misuse) your ult on a single champion. When surrounded by multiple enemy champions Xin's ult does much more team damage and can make the difference in the fight. Also, remember to use this ability early in the fight to inflict the most damage since the ability is affected by your foes current amount of health.

First off, this is not a jungle build. Xin is much better laning because he is powerful at low levels. He loses this advantage mid game which is where a jungling Xin would begin entering team fights. But dont fret, Xin is a great late game champ. The best option is to be aggressive from the start. Building your Charge first allows you to initiate at low levels from range and squeeze out kills with ignite. Gaining kills early nullifies his mid game lull by allowing Xin to purchase stronger items earlier. A Goal to shoot for is to have your boots and blood thirster by lvl 10, but the earlier the better. Depending on how aggressive you are, teleport might be another option on your summoner spells so that you can b and return quickly.
This build follows the idea that they cant kill you if you steal more life than they are dealing. If you sprint to your first bloodthirster then you are pretty set with attack speed runes. The frozen mallet creates a constant slow which makes him great for ganks along with ghost. This item also makes him more sturdy and opens the option to attack multiple targets under the right circumstance.
Another option to grab that early game dominance is stacking Doran's blade. It covers all of the areas you are focusing with your later build. However, be careful not to go over 3 blades, because they resale at half price and this will delay your bloodthirster. A common build i see with Xin is a dash to zeal. Though this gives different advantages earlier, the attack speed runes and ghost make up for not building this item until later.
Late game Xin turns into a thief. He is quick, sturdy and has a fair amount of attack. Xin FTW!

Blood Thirster, Frozen Mallet, Phantom Dancer

Mercury TreadsRather Than Berserker's Greaves
Also, magic resistance is extremely important versus teams with mage nukes such as Ryze or Malzahar or simply against teams dealing a lot of AP damage.
Banshee's Veilor Force of Nature

Because Doran's items are now more expensive, going with long sword to get some early damage is your best bet. This enables you to grab a health potion as well. His lifesteal is too weak at low levels to depend on for gaining health even with Doran's Blade's increased lifesteal.
It is possible to mid with Xin (take the middle lane solo). In this circumstance you must switch from passive and defensive to aggressive at a moments notice. You sit and wait until the enemy champion gives an opening, i.e. they use a vital ability on minions and it is on cool down or they take too much minion damage, and immediately turn to offense.
But still, laning with a tank or a stun is the most preferable situation.

The primary issue with Xin is though he is a great initiator, he is quickly targeted once he enters the fight. He can kill enemies quickly, and is almost impossible to solo dps late game, but his health and armor does not permit him to be focused by an entire team. A hit and run tactic can solve this issue.
Initiating a fight after your tank, kill an enemy, then assess how the fight is going and retreat if necessary. Often opponents will chase in hopes to gain a kill, but this will string the opposing team out and allow them to be finished one at a time. This tactic does not guarantee survival, but it increased the chances of your team winning team fights.
However, running is not always necessary. Most times a late game Xin will never have to leave a fight. On the contrary, staying will allow one to steal life more rapidly and leave the fight with possibly more health than you entered with.