MITM Wireless Adapter?

Hi! I'm thinking about getting an alfa wireless adapter because I really want to do some WIFI hacking and I have been having trouble with my Man in the Middle Attack.

I'm not sure how I would 1, set up arpspoofing with my wireless card, 2, put it in promiscuous mode, and 3, look at things like urlsnarf and driftnet.

Any ideas? Anything is appreciated. Thanks - Cam