Things I have learned in a decade of insecurity:
1. People almost never notice your “flaws” as much as you think they do.
2. No matter how much you dislike X feature of your body, there are people out there who will think you are drop-dead gorgeous, guaranteed.
3. Good clothes and makeup are great investments – not necessarily because they make people like you more, but because they make you feel prettier which means you’ll take awesome risks socially that you ordinarily wouldn’t have (i.e. you’ll be more confident).