Ooh, that's a hard one. Confidence is something very much internal and there isn't really an effective way of "faking" it, nor would I advise such a move. It has to come from inside, you need to
know your worth. For me, it was a process that took years and involved various situations in life that "tested" my true character and beliefs. I think the only way to build confidence is by challenging yourself and seeing how you hold up to those challenges.
In the case of girls: practice makes perfect. Just go up and say "hi". Don't think any girl is doing you a favor because she
isn't. Come up with a confident smile and strike up a conversation (otherwise known as hitting on them
). Don't take it personally if you're shot down, know that its their loss. You can be humorous and gracious about it and move on to the next girl. Don't make her think she's too important to you (in the initial hitting on stage). People want what they can't have. Also, if you are shot down don't take it to the opposite extreme of acting as though she is a worthless bug or some other kind of fiercely negative emotion toward her. That gives her too much importance. The thing is,
any guy, even the "successful" ones, will generally get 10 no's for every one yes. You're not alone. If you're still in the learning process, perhaps try hitting on girls you aren't totally bonkers "wow she's such a hot bombshell!" about and instead are more "wow she's pretty/cute/etc." about. You'll be more confident and put together and as your success builds, so will your confidence.
In any case, that's as much as advise as I could muster on such a subject. I've never hit on girls so I'm not such a guru on the topic