I've used a few builds for Wukong, however I feel that they are not as effective as mine. The reason is because they dont seem to put out as much damage in my opinion. Please try out my build and tell me how you think it is.

Pros
-Excellent early game damage.
-Easy to escape ganks. Also easy to get in and out of fights to harrass your enemies. (Activate crushing blow, nimbus strike enemy, hit with crushing blow, decoy & run away. Repeat.)
-Low mana costs (You will be using lots of mana though to harrass your enmies.)

Cons
-Squishy early game. (However if you use decoy properly, this shouldnt be too much of an issue.)
-If you are doing well, you will be a target to focus.

I feel that flash is not as necessary with wukong because you can easily juke enemies with your decoy, if you use it well, that is. If you are not that good of an escape artist then you can replace ignite with flash. I prefer exhaust and ignite, because it almost guarantees the kill for me. Also you can use ignite on your enemies who run away with low health, which does happen very often.

Most guides I have used say to upgrade your crushing blow first. I feel that I do more damage if i get two points in crushing blow early on, then max out nimbus strike next. Nimbus strike does great damage, and since you max it first it makes chasing enemies much easier. You can also use it to escape if you need to. If you are in lane phase or just happen to be running through a lane near enemy creeps you can nimbus strike to creeps which increases the distance between you and your enemies. I also like nimbus strike because of the high damage early game, which is great with the attack speed bonus you gain from nimbus strike.

The reason i get a brutalizer early on is for the damage and cdr, which is extremely helpful. Upgrading it to youmuus ghost blade is not needed until later because you will only gain the increased attack speed/ movement speed. You will gain this anyways from the trinity force that you build after the brutalizer. Blood thirster and Trin force add damage and help you stay alive in battle. I get the Phantom Dancer to make me fastere, and since you bought alot of attack damage items, the attack speed and crit chance is extremely useful.

close enemies that can not run from you: Nimbus strike into them, auto attack once, activate and use crushing blow. Then use Decoy, and you can either run away or move behind your enemy. IF you use this combo quickly enough you should make it to decoy in time so that your enemy uses all of their burst damage on your decoy, and then you will appear behind them, and destroy them hopefully. If they try and run your nimbus strike and crushing blow may be on cooldown, and if not, it should be off cooldown while you chase them.

Enemies that like to sit back with low health: Enter a bush and get as close to an enemy as you can without leaving the bush.Activate crushing blow, then use decoy, and run to your enemy as quickly as possible. Use Nimbus strike when you are close engouh, then use your crushing blow which is already activated. Exhaust your enemy if you need to so that they cannot escape. If the target has a good bit of health before you enter the fight, ignite them immediately after exhausting so that you can ensure the kill.