Be really, really confident. Looks mean nothing when compared to confidence.
Seriously, despite massive issues with trust and thinking I look horrible and generally not being the most attractive person (although all of these are becoming less so; I'm kicking myself into trusting my friends and I actually am becoming more confident), I can still attract girls just because I cover it all up with confidence, often bordering on narcissism. And a willingness to mock myself probably helped.
Worry less about how you look (it's not completely irrelevant, though; if you grow facial hair, keep it looking neat, or stay clean-shaven, and stuff like that) and more about how you act.
So, basically, rock what you've got, as Rutskarn said. Apparent total self-confidence is a wonderful thing.