Hello!
I am Tna and this is my Xin Zhao guide.
Remember, this is a guide, not an instruction, so your builds should vary depending on the enemy team,
however there are a few core items a good Seneschal of Demacia should have.

Masteries are bugged on the page. 1/16/13

not anymore but I'll leave that cause it looks like I'm boss.

In this chapter, I will discuss the jungle route I use (I'll provide video guidance as soon as I am at my hometown, since I am on a ****ty notebook that cannot handle LoL).

My jungle route is odd, but it's damn fast (Level 4 at the 4 minute mark), that's all I can say about it.

Start as usual: [x1 cloth armor] + [x5 health potions]; then head straight to the Neutral Golem Camp.
The second golems spawn, smite one right away, then attack once and continue to kill it with one Q (3 Talon). Finish the other one with autoattacks and Q (3 Talon). Level up W (Battle Cry) and head to the Red Buff spawnpoint.

IMPORTANT: Time your W (Battle Cry) to reduce the cooldown on your Q (3 Talon) to maximize the time the Elder Lizard is disabled..

By the time you're done with killing the smaller Lizards, your smite should be ready to use.
To have no downtime smite the Big Wraith as you're heading to its camp.
Finish the smaller ones and move towards the Wolves, start from the big one and continue to the Ancient Golem. F
rom this point you will start maxing E [Audacious Charge]. If you were fast enough your smite is not even up yet. If it is just smite whatever you want for the +5g, since you'll be Recalling anyways.
I tend to grab boots and some more potions since you'll be ganking by this time and they guarantee a kill.
The cloth armor will develop into madred's razor => bloodrazor lategame.

TL;DR: Q>smite Golems W> Lizard W> smite Wraiths> Wolves> Ancient Golem E> Blue Pill

Magic Penetration Marks

Odd rune choice, but before you start going:
-LAWL MAGIK PENETRETION RUNEZ? U FKIN NUB OMG LERN TOO PLAY XIN ZAO U NEED ARMOR PENETRETION!;
Just hear me out.
The reasons for this Rune choice are quite obvious to me, but not everyone so I will state them in points so it's all clear.

♥ 2 out of 4 Xin Zhao's skills are Magic Damage, that is Audacious Charge and Crescent Sweep - the most important skills, the skills you use to initiate.

♥ 2 of the core items in this build dish out Magic Damage: Sunfire Cape and Madred's Bloodrazor.

♥ Madred's has synergy with the other 2 skills out of Xin Zhao's Skill sheet. The attackspeed makes you dish more magic damage the more times you land a hit, and 3 Talon is just basicly 12% of your enemies health gone just from the passive, need I say more?

Pros:

♥ Insane damage output
♥ Jungle God
♥ Great ganking ability
♥ Great initiator to combat

Cons:

♥ Lux is an ugly *****

There is no alternative for this skill build, this is the only viable choice on Xin Zhao. Whatever Three Talon Strike does, Audacious Charge does better.

Three Talon Strike:

Damage: 15/30/45/60/75 each continous attack for the next 3 attacks.
At level 5 it is 225 Damage.
Cooldown: ALWAYS 10 seconds
Knock up

Audacious Charge:

Damage: 70/110/150/190/230
At level 5 it is 230 Damage.
Cooldown: DEPENDANT ON LEVEL 16/15/14/13/12 seconds
Slow: DEPENDANT ON LEVEL 20/25/30/35/40 %

As you can clearly see, leveling Audacious Charge gives you far more than leveling Three Talon Strike.

For AP Heavy Enemy Team:

(example Nunu, Corki, Sona, Vladimir, Warwick)

Swap Atma's Impaler + Warmogs Armor combination into a Force of Nature and a Spirit Visage.
If the enemy team is not that AP based,
but still has a lot of AP damage (Corki is a threat) consider grabbing Wit's End.
It will boost your damage output + it gives you the extra edge you need against magic damage.