Xin Zhao is a very capable jungler. He is very powerful ganker, and puts out insane damage the entire game. He can carry teams and if played right, can win games by himself.

Marks: ArP*
Seals: Health*, Dodge, Attack Speed
Glyphs: Attack Speed*, MR, MR/lvl, CDR
Quints: ArP*, Health
* recommended

Core:
Wriggle's Lantern: Great jungling item. The life steal, and ward are also very useful.
Frozen Mallet: A bit of survivability and the slow makes it easier to chase.
Mercury's Treads, Boots of Swiftness, Berserker's Greaves: Entirely your choice.

Situational:
Bloodthirster
Infinity Edge
Wit's End
Force of Nature
Warmog's Armor + Atma's Impaler
Black Cleaver
Guardian Angel
Banshee's Veil

Start off in the bushes just outside blue buff in the river. This will allow you to see if the enemy team is coming to gank you.

1. Start off at blue buff. If your new to jungling, get an ally to leash blue for you, so that you won't take as much damage. Pop a health pot the moment you take damage to minimize the amount you take in the long run. Make sure you make use of Xin's double attack combo (auto attack, then immediately after use your Q, and you end up doing two attacks in a very short time). Keep hitting the golem, and use Q whenever it comes up. Smite the golem and finish off the creeps. Keep in mind that you will be very susceptible to a gank right now. After killing golem, I am usually at low health, so make sure you keep one eye on the map to make sure there aren't any MIAs. You should level up at this point. Put your skill point in W and head on down to wolves.

2. Wait for the CD on your Q, then attack the biggest wolf first. When your Q goes on CD, use your W, and keep slapping it. Pop a potion if you need to and keep spamming your Q. Because you have blue buff, you aren't too mana dependent at this point so feel free to use your abilities as much as you want.

4. By now, your Smite should be off CD (if not, wait a couple seconds for it to come off). Walk over to the wraith camp and smite the blue wraith. Make sure you tell your mid lane person to go away so that they don't accidentally leach XP from wraiths. The other wraiths should fall quickly. If you are low, feel free to use a potion. You should be level 3 now, so put a skill point in you Q an head over to golems.

5. Use your Q and W combo and clear the golems. If you jungled decently, you should have at least one pot left and about 75% health. If not, go back to base, and buy some more health pots, and some boots. If you do have them, head on over to red. You might have to wait 20ish seconds for Smite to get off CD. I recommend waiting in the bushes next to red, until Smite has 10 seconds left, then engage the lizard. Use your Q, W combo and pop a potion the moment you take damage. Throw on Smite to kill him, and finish off the remaining creeps. You will be very low at this point, but you should be able to survive. You should level up, so skill a point in your E. If you still have one pot remaining and the bottom lane is pushed back, pop the potion and head over for a gank. If not, base and purchase Madred's Razors and boots if you can. It is always good to purchase Health Pots on Xin, because he needs them to jungle effectively. Also, as the jungler, it is your responsibility to ward the map.

6. Once you hit level 6, you can solo dragon. Use your ultimate to nuke dragon at the start of the fight, and then proceed to use your E and Q, followed by your W, so that you can effectively spam your abilities. Use Smite to finish dragon off.

After this point, you should continue ganking lanes and farming the jungle. You are an amazing duelist, so don't be afraid to attack the enemy jungler in the jungle. In Mid/Late Game, you will be the focus of the enemy team if you are doing well. NEVER INITIATE. Wait for a fight to start, then dash in on the enemy carries and wreck havoc.