You were likely sending singles you weren't aware of through your body language. Women are very sensitive to this, much more so than men.

Women are like mirrors. they'll reflect what you show them. So, if you are nervous and uncomfortable, she'll feel that vibe and become nervous and uncomfortable herself and she'll want to get away from you.

My advice is to go in and talk to as many women as you can WITHOUT ANY AGENDA. Say hello, introduce yourself, shake her hand and ask an open ended question to start a conversation and let it flow.

When you run out of things to say (and you will), tell her it's been a pleasure, but you need to get back to your friends. Take a step away, then go back and say "You know, you seem pretty cool. Give me your phone number and I'll be in touch in a day or so." When you step away she'll feel a sense of loss and will be more likely to give you her number. Also, do not ask for her number. Tell her to give it to you.

Talk to at least ten women every time you go out.

Don't let them get you down. We all get rejected more than not. This isn't hunting, it's fishing.

I almost forgot.

Look her in the eye and don't forget to smile.