Rule #1: Be cool. Never let 'em know how interested you might be:
Rule #2: "The half-smile" - When you make eye contact, give 'em a glimpse of what's to come:
Rule #3: Find a common interest (no matter how weird you think it is!):
Rule #4: Display feats of strength (ie pushups!)
and lastly ... if all else fails...
Rule #5: Show 'em a little toosh!