You just gotta have a fresh style, be well groomed, and sort out any body-language issues you may have. I hang out with old people, young people, women, married guys, guys who suck with women, etc... However, when you are actively trying to pick-up women out at 21 establishments it pays to go with a buddy or two who will help you in your quest. So you should go out with at least one friend if not 2 or 3. You want these to be guys you like, and can have fun with.
Talk to your buddies, have fun, make jokes, check out all the sexy women. Then when you see some girls you like, approach them together and help each other out. A lot of times girls will be more open to leaving the bar/club if it's you, your boy, her and her girl, instead of just you and her.
Every guy would like to be able to bring home ladies he meets at bars. Women can sense if you're needy for sex/female validation, and it skeeves them out.
The guys who attract lots of women aren't needy for them, because they already have them.
They might think they are, but their poor results speak for themselves.