hm, you could change your hair. color, length, or style. you could change the way you dress. maybe to something that would be a little out there for you or that you normally wouldn't consider wearing. you could always get a piercing, but that's a bigger commitment and your under 18 so I don't know how ya family would react.
i would say dye ya hair bright red if your daring. I think it looks amazing lol. plus your at an age were you can still get away with it : P
If your hair is long try cutting it shorter. A girl I know cut 10 inches and it was like she was a totally different person (in a good way). It's not super short. It's about shoulder length. It definitely made me more attracted to her. Not that that would be why you're wanting a change.
I would say change the way the style of your clothes are into something that you never wore before but wear it presentable/desent, get a new hairdo, apply makeup but not too much or if you want to put on gloss. I would say gloss is better. Try getting your nails done or something that is different.