This article shows the perceived links between looks and earning power. If you are tall, slim, and gorgeous, you are likely to earn more, yeah? Seems so.
However, I had a suspicion that if I read through to the end they would come to the real crux of the matter, and they did: self-confidence. I think the most important factor is not the looks themselves, but the self-confidence they inspire. And while outer factor can make it easier for you to have and project self-confidence, it's really a mental thing which can be built up, not the least by simply getting your job training and doing really good work over time.