Don't worry about being cool - worry about being you.
You will always be your best advocate - don't let anyone make you do something you don't want to do.
Own up to your mistakes.
Love your life.
I may not know what I want to be when I grow up, but I do know that someday I want to live in a house filled with my books and travel souvenirs. And the walls that are not covered in bookshelves will be covered with photos of my family and friends. When I leave the house I will be going to a job I love, and I will return to a person I love. So, that is the dream I am working on.