Giving Green Lights
Most guys are terrified to approach a cute girl at a bar or party because of the rejection they could possibly face. The idea of walking back to their friends without a phone number is too much to bear. Even if you glance over at him once, he might think you're just looking for a friend or your boyfriend.
Always smile and give off that positive energy - that's the most important thing. Think about the person you notice most at the party. It's probably the one laughing and telling stories and has a group of people around them. There is an energy about that person you just can't describe other than magnetic. Maybe you've thought that you could never be that person but all that person is doing is just being happy. They aren't worried about how they look or feel any embarrassment.
Sending green lights includes smiling and holding eye contact. Find a way to stand next to him at the bar or near his group of friends. If you overhear something funny, look over smile and laugh. Become engaged with the crowd and just make yourself open to opportunities. Avoid saying anything negative but it's OK to tease a little. Don't put down other women or you'll come off insecure. Think about how you'd like someone to interact with you upon first meeting. You probably only want to chat with happy, positive people when you're out. Not someone who is bringing the mood down.
If you don't feel comfortable making the first move yet, at least try to stand with your face towards the crowd. Don't stand in a circle with your friends closing yourself off to anyone new. That body language screams, "Don't talk to me!" Facing the crowd invites people to approach you. Also watch what you're talking about with your friends. You never know who is overhearing you. Try to keep the conversation on topics that you wouldn't mind a potential new love interest listening in on.
Try this out next time you're out and let me know if you notice any differences. Good luck!