My first priority is to get a little attack speed because you need the stacks on your enemy when you're using your abilities. Obviously you're getting faster stacks when you hit faster.
After that I'm going for more critical hit rating and damage. That could be "Infinity Edge". An important fact is also to get life steal. which could be "Bloodthirster". You need the damage aswell. I've also chosen "frozen mallet" because I think it's important to have a little more health. Twitch is as said an easy target.
The build of cause depends on who you're against. If you're fighting against lots of tanks you should probably go for "last whisper", "madred's bloodrazor" or "black cleaver" instead of all this attack damage which is better vs tanks.
On the other hand if you shouldn't you'll be allright.