Too ugly to hit the dancefloor, too stupid to talk to that gorgeous guy? You're not going to spend your life being held back by that sort of thinking, are you?! The only way to get over your hang-ups is by making an effort! To reassure yourself, take one step at a time.
The simplest way is to start by gradually dressing a bit more sexily, more originally and more fashionably, without throwing out your old wardrobe. When you get to the stage where you're wearing a full outfit you'd never have dared to wear before (skinny jeans, a dress and boots, for example), you'll start getting compliments, not jokes and nasty remarks.
What could be better for encouraging you to tackle the following step than your relationships with others. If you're more stylish, you'll feel a lot more comfortable approaching that guy you've got your eye on!