At level one You should take E, for and easy 1v1 fights. It deals average damage, good for poking/escaping and gives You AS. The, max Your Q for poke (literally, lol), damage and A. Penetration. Your "Decoy" spell is good for damn jukes, but kinda useless and fights, so take it at level 4 and max it last.

Juking as Wukong easy and REALLY important. Sorry, I cant upload a photo/video, but I'll try to explai it:
Imagine You are top lane against enemy Yi. You are low enough, He's full, He uses ult, Q and what do You do?
FIRST: DONT DECOY UNTIL HIS GAP-CLOSING SKILL ENDS!!! He can easily spot you like that.
SECOND: USE BRUSH! Using Decoy near brush can really confuse enemy. As an example, You run right directly into Your turret, use decoy that looks RIGHT DIRECTLY IN YOUR TURRET NOT IN THE BRUSH and run into brush. Your enemy will probably keep chasing You into turret, while you escape threw jungle.
THIRD AND LAST: S! While running You can press "S" in your keybord. It looks familiar like You used your W, so enemy will keep running towards, while You stand afk. Then use the real decoy ( when the enemy is far away ) and he will be confused as a penguin in a local market. PLS DONT DO THIS AGAINST LEE SIN IT JUST WONT WORK OUT.

Wukong has a CRAZEE combo, that no one know about, it helps you to harass enemies BADLY.
NOTE: DO IT WITH FULL MANA OR AT LEAST HALF OF IT.
FIRST: Press Q but dont use it, then E ( Nimbus strike ) on enemy, smack him with Q.
SECOND: Just drop a decoy like a baws and walk away. Enemy will think that You are going on him, spam his skills, ults, summoners on Your decoy then POW! HAHAHA! They realise its a Decoy. I've beed solo top against Darius, did this combo, so he ulted, ignited and then flashed away 'cuz he was pretty low on hp. When he saw decoy exploding, he raged on me like my mom does when I dont clean my room.

1st: Use ghost combined with Your ultimate.
2nd: Wukong's E ( Nimbus strike ) is not only an offensive move, it can be used on minions to escape skirmishes.
3rd: Dont be afraid to initiate teamfights, dont forget Your passive, it looks useless but believe me - ITS GOOD
4rd: First use Your Q, then E and attack speed boost ( A. Pen from Q, DUUH )
5th: Dont accept ganks without mana and ult. Enemies will just flee, but it depends on your jungler's CC
6th: Wukong is a good assassin, use Decoy while in brush and while You are stealthy, use E on enemy.
7th: FOCUS SQUISHIES.