The only way to get over any kind of fear is to face it head on. If you need to have a couple of shots to get more confidence, then do it. Fake it until you make it. It works every time. Once you start to approach women and see that they like you, you will lose your fear of rejection. But you must take that first step. Try approaching a woman you aren't that really attracted to practice with, then keep practicing until you have the confidence you need to approach a woman you are really attracted to!
People attract what they fear. If you fear rejection, you will receive it. Just go out by yourself some night and approach a girl who doesn't really seem that appealing to you, and it wouldn't make any difference if she rejected you or not. Get a little confidence, then move on to another one you are more attracted to. Practice makes perfect. Pretty soon, they will be flocking like bees to the honey!
I used to be really shy, but I learned to practice being confident and pretty soon I became more confident. FAKE IT UNTIL YOU MAKE IT. Very wise words!