I've noticed that when I go somewhere with a friend, even if just one, I feel like I can hang out forever. While, if I were to go to a bar by myself, even though that's easy to do, it's not fun - I feel über self conscious (everyone is looking at me / even though that is probably your false perception).

When you go to a bar by yourself, you have to invest a lot of your energy to initially meet people (think of the times when you've been travelling and in a place where you know no one).

And, on the social side, when I am out with a female friend, I feel even more confident and feel like I have license to flirt shamelessly with near everyone.

I feel going out with friends can give you the support base to go out and venture. However, too many friends can devolve into the classic circle-the-wagons formation. Of course, there is the social hack of working the room that nearly always works and requires fearless action: start with one, engage him/her, offer him/her an opportunity to approach with him/her to a group or leave, engage the group confidently, wave at someone in another group, etc. Done confidently and charmingly, it is quite a feeling / to bootstrap yourself from a loner to someone other people are looking at and wondering 'who is this guy?'