Start off simply: laugh and have fun with the guys. Don't make it a big weird thing, but also when you see an attractive girl go up by yourself and say something. What you say should depend on context and your personality. Personally, I usually go semi direct, I will either comment on something about them or the situation (ie. if I am going to the post office and having envelope in my hand, if I see a girl I like jokingly say "One to go on the romantic date to the post office with me?")
The most important part isn't what you say, but a combination of :
- How you say it/confidence/vibe
- Your sexual market value.
- How much you are the girl's type.
- The girl's current emotional state.
I am sure the UMP guys can extend on this a lot more

15 Posts (+31), 492 Cmts (+149)
You are asking the wrong questions. Do not start gaming.
Hit the gym, get better clothes, fix your hair and image.