I will echo what others have said here. I remember having troubles when I was young when all the kids started "dating". I was just so scared. I had a little luck, but really it was all luck, bascially the girl would have to come to me. Then around 17 or 18, I just started thinking, what the hell do I care if a girl says no?
So like others have said, just start up a casual conversation. You'd be suprised how often that works. If they say they aren't interested, say that's fine and chat a little longer. No need to look like that was your sole intention. Sometimes that is enough to show them that you aren't necessarily looking to just bang them, but are actually interested in them as a person.
Also, booze helps, but control yourself. One issue when I turned 19-22 or so was I would go out and get just plowed and if one of your buddies is more sober, he stands a much better chance. So drink, but don't be the wasted guy if your goal is to meet ladies. Of course, some nights are just about drinking too