Ways we socially define beautys?

I doing an essay for english and my topic is "ways on how we socially Define beauty" and my topics are elaborating on the bottom 3… and i need examples for each….. Im also having trouble conducting a thesis with all my ideas… PLEASE HELP!
1) we are taught to believe whats beautiful, due to media
2)Stereotypes about beauty…
3) The issues Light skin vs. Dark skin