The best books about body image (for girls anyway) are the gURL Body Book and gURL's Deal With It. Those books kept me sane through high school. XD

Those books have a great point about what people find attractive -- a lot of it has to do with personal experiences. Like, I think fat girls are really pretty because I knew so many awesome fat girls growing up. And guys who look like the bully who picked on me in seventh grade, or my mean 11th grade teacher gross me out, even when other girls think those guys are cute!

So really it's silly to try to appeal to everyone, because everyone has a different idea of what's attractive. I guess you could try and mold yourself to appeal to the the widest possible range of people, and that's what some people do. But that's SO FAKE. It's way better to just look how you WANT to look, because that way you'll attract people who will like the REAL you and not some fake front.

(It's easier said than done, I know. XD I'm still working on it. But that's definitely my philosophy!)

So anyway. Read the gURL books!! Also, look at old paintings once in a while. Titian, Botticelli, Rubens, etc. Check out the Venus of Willendorf!! Learn about what cultures have found beautiful over the years. What's "hot" changes ALL THE TImE. It's pointless to waste too much energy on something so transitory.