To be hotter you got to stroll the fine line between hot and sexy by finding the right balance. Not too much make up, just enough and it should not be too much skin, just enough. Then don't go around showing your belly if it's bigger than a blimp and covered with stretch-marks, don't wear low riding jeans if you are going to look like a muffin top. Make sure you can really walk in heels or you will look stupid instead of hot and most important make sure you can pull it off.
You already have hot friends. Maybe they like you because you have something they envy. Why change that? And become competition? Girls like you are the ones who usually get married for the right reasons. Don't change for the wrong ones. :)
Well, personal hygiene is a MUST. Keep up with some of the styles, but mostly wear clothes that fit you and aren't the wrong size. Don't over do the makeup, you will look like a clown. In my personal opinion, just act yourself and don't worry too much about your appearance.