First and foremost you need to realize that God and Mother Nature doesn't make junk or ugly people so you need to realize that you are the most beautiful person you know in the Universe and let no one tell you any different.
Now the real beauty comes from deep inside each one of us and you may be good looking on the outside, you may not be releasing the true inner beauty you really want people to see. Talking to the opposite sex is never easy but until you start, youll never break out of your shell so all you can do here is try and be prepared to be shot down. No one wins them all, not even me and I can talk to anyone.
A secret for life here is once you do find someone that really interests you, do your homework and find out their likes and dislikes and then find a like that is common to both of you and build off that, but take things real slow and let Nature take its course. So be friends first and don't treat her any different if you guys are around your friends or hers or its instant death if you treat her any differently. But try saying Hi to all you meet and see what happens, but this is only to get you to start opening up and showing people that youre not stuck up.
Another good thing many public speakers learn is no matter how scared you are at doing something, try not to show it. But youre still young with a whole life ahead of you but start trying to be a little more aggressive and outgoing and good luck and please let me know how it goes or if you need more advice