When the game starts, make sure you buy the ring of doran (to make aggressive damage thanks to the poison) and to remain rather safe. You will need to farm on average up to level 4 before you can really impose on top plus your mastery ensuring a constant casiment regen HP.

From level 6 and if you bought the statikk Shiv, phantom dancer and vampire scepter you can gank easily with the combo: A + AA + Z + AA

If you have followed all my advice and you have remained safe in early while filling a maximum you should then have already destroyed the top and its turrets thus securing for you a very large amount of PO. Now we are in late game .. the moment when all the champions begin to show their power .. Your half-finished build you should have the Strattik Shiv, the Phantom Dancer, The Bloodthirster / The Blade Of The Ruined King, and maybe the Infinity Edge ... This allows you to calm down very quickly all enemy champions wanting to approach a little too close to your favorite yordle. If you get to finish your build before the end of the game you can very easily return the game and win this game to you all alone! :)