Focus on early harras with the w and maximize it first,it will deal extra damage,it can also help you to take the blue very easy.
Don-t use yout e on farming minons,only on pushing,you can never know when you need it.
Never forget about the Zhonya's/Deathfire.
Use your zhonya when the team is coming towards u if u are fighting like 1vs5,but if they aren't coming use your e and ultimate to slow them down and ping to them,if they catch u wait until using the hourglass.
For the deathfire use it at the begging of the combo R-W-Q-E.
Your Q will do the on-hit effects so activete E then use Q for bonus damage.