You don't need to get meditate unless you level up during a fight and think you're gonna need it to live. As for Ghostblade just get it as your last item (If the game last that long) and sell your boots (Hoping your occult is at 20 for that attack speed boost).
As for lanes just wait till you're on your double strike and then Alpha Strike champion hit them and run back just keep harassing early game till you see a opportunity. I always lane mid but once you get Malady you should be set to Jungle get the mana aura and start Alpha Strike all groups for quick exp and money. Late game you should be 3 shotty some heroes (Ashe, Ryze, Ezreal etc.) and should be able to handle killing tanks in no time. P.S. You're not a tank don't try taking a group on without your friends.

Abilities:
Really all you're using is Alpha Strike and Wuju. Before level six while laning if you're mid then just wait for your double strike and Alpha Strike/Wuju the enemie champion hit them with the double strike and run away. If your in a lane with someone else don't use Wuju incase they might initiate a battle.
After level six you don't really have to wait for double strike you can if you want and it'll be better all you have to do is ult wuju and alpha strike into the enemy and just chase them down till they die. Most of the times they die pretty quickly.
If you're going up against Karth you might want to get meditation before he hits level 6 so that way you can use it when karth uses his ult (making his ult take close to nothing).
You're ult is also very useful to running away and if your chaser is fast just use ghost also.

Spells:
Ghost- Used to chase or to escape very useful with your ulti since you can't be slowed so it's an awesome initiator and to chase or run.
Exhaust: Always use it on the strongest person that way you can concentrate on maybe a caster while fighting someone who takes massive damage to you and then you can kill that person next with ease have a 1v1. Or if it's a 1v5 just exhaust someone who you think is most lethal as a physical damage dealer and kill them and then the rest. also very good for chasing you slow them down and kill them easily without having to tower dive very good to get FB.

Gameplay:
Early Game (pre level 6): Early game if you're going against a ranged just use Alpha Strike hit the champion with double strike (While you have wuju activated) and run back. If you're going against another melee just do the same thing but attack them when they start running close to you (Unless they have a stun in which case just stay with the "ranged" plan). If you see an opening where they might have like 200 - 300 hp alpha strike and kill them then run back. You should get first blood before the creeps come out if you get a good gank in on your lane. If you're mid you can still get first blood just keep harassing and don't let that chance escape you. By the time you hit around level 5 you should already have a Malady when you have Malady you should go get your auras (mana first) and then start going to lanes helping your team mates and get kills (GET FED).

Mid Game: (6-16)
Now you should have your auras and a few kills in just keep up the work get your greaves and start running all over the place kills creeps and minions in the lane. In no time you should hit level 10 when you do you should have parts of Dancers and already have malady and greaves this means you should go kill the dragon every time he pops up he gives good gold and exp to you and your teams it'll help out a lot. By the time you hit level 12 or 13 you should have dancers and occult maybe or have at least started getting occult. This is your peak your dancers give awesome crit attack speed and dodge. Now you can run into fights get kills quickly and run away with ease. Just try not to get stunned. If you see a Ryze alpha strike him as an initiator so his snare wont hit you till you're next to him. Stuns are your worse enemys so (Sion, Taric, etc.) don't solo them in a team fight or they'll stun you and it's all over. You should be level 16 or so now and should be well on your way to infinity edge and have a nice stacked occult. At this point your pretty strong so don't worry about dying in a 1v1 even against a tank (without blackthorn mail) you should always win a 1v1 no problem. By level 16 you should have infinity or almost have it and should be killing everyone no problem.

Late Game: (16-18)
This is pretty easy now you're fed and have low deaths and high kills (or should). If you're not killing a lot by now you should try to play a little more defensive but once you have infinity which you already should go for bloodthirster and team fights 1vs 5 you should be able to kill 3 or so if not all (Still assuming no stuns) and just remember tanks always die first. Just make sure you catch them off guard and go for the squishiest person there. Only time you wont win a 1v5 is when they have chars with a lot of hp like poppy or panth or xin they may not be tanks but they'll take a few hits maybe 4 or 5 and thats 2 seconds to much. So just take them with your team and make sure you always have your team near you at this point because everyone has a almost full build and is pretty strong. You should be going for Black Cleaver by the time you hit level 18 and when you have almost enough to buy it you sell your greaves buy a potion of fortitude if you want use it and then buy black cleaver. Now this means tanks for 0 problems to you and those non squishy fighter heroes are just as squishy as ashe to you. Soon enough this is gg and your team wins.