For a start lots of that is personal opinion. So that varies between people. Some people have features that are more commonly seen as attractive however.
People have suggested the amount of symmetry a body has affects how ‘good looking’ they are with people who have more symmetrical faces being more attractive (to a wider group of people) than those who don’t.
At the end of the day it is down to style, taste and their confidence. But there is some interesting science behind some of it!
Yes, I agree with this too – someone can be attractive for lots of different reasons, not just looks!
Studies have found that looks are quite important though. Like Tom says, the more symmetrical someone’s face is, the more attractive most people think they are. Scientists have done studies where they have shown people lots of different faces (ones that are supposed to be very attractive and less attractive) to see how that changes someone’s behaviour toward a person. People were actually found to help attractive people more!