Step 1: Doran's Shield / Blade.
Step 2: Gank people.
Step 2a: Boots of some sort, preferably Beserkers, unless you can hard counter 2/3 of their team with Ninja Tabi / Merc Treads.
Step 3: Sheen.
Step 4: Gank people some more. Don't forget to farm the neutrals for buffs. Movespeed and Lizard slow = easy mode ganks.
Step 5: Zeal / Phage -> Triforce. Phage first if you feel you are too squishy, Zeal if not.
Step 6: Go forth and wreck people some more.
Step 7: Some other DPS item, Black Cleaver, Bloodthirster, etc are all good.
Always play conservatively, since you are melee DPS you don't want to tank if you don't have to, and you have a hard time getting into the fight first and then getting away.
Turtle, Bear, Turtle, Tiger, Turtle, Tiger, repeat until turtle and tiger are maxed. Only use bear to stun iniate and to chase/escape. Other than that you should be popping Turtles for bursts, and Tigers for DPS.