Start with Boots of Speed and 3 Health Potions.
Go on with Sheen for your Q and Elixir of Fortitude for more AD and Health limitated. Take Berserker's Greaves. After, finish Trinity Force and take Vampiric Scepter for lifesteal. End it with a Bloodthrister and go on with an Infinity Edge or a Last Whisper depending on the other team. After however take IE/LW.
If you're the most feeded take a Black Cleaver, if you aren't finish the build with Guardian Angel.

Cause your Early Game is great for harrassing using your W, it's better starting with Mejai's Soulstealer for your damage and Rylai's Scepter for your HP. For drastically increase your Ability Power take Rabadoon's Deathcap. After this take Lich Bane for make your Q good as the other skills. Take Void Staff, Zhonya's Hourglass or Abyssal Scepter depending on the other team.