Step 1: get sufficiently drunk to feel confident enough to approach a girl and dance a bit, but not drunk to the point where you run the chance of puking on her or falling asleep.
Step 2: Scan the place. Although looks are important, usually the most important thing is to find a girl hammered enough to not be too picky with guys.
Step 3: Slowly approach her on the dance floor while dancing (preferably with a friend, so that she does not think you're a freak).
Step 4 (strictly optional): Try to say something witty. This does not have to be more than one line, nor does it, in fact, need to be witty. By that time, most probably both of you would be too smashed to even care.
Step 5: continue dancing, and every once in a while act goofy to keep her interest and keep her laughing.
Step 6: Slowly start to wrap your arms around her.
Step 7: Kiss her.
Step 8: make sure you have protection.
(Disclaimer: the author does not take any responsibility for adverse effects or consequences that may result from following the steps in either The Rules of Attraction (1) or (2))