Do you know who you are? Do you know what you want out of life? What motivates you? What do you love? What makes you laugh or cry? What makes your soul sing with joy?
What you look like doesn't really matter - it doesn't make you who you are. People that think how you look is important are shallow. Sure, be the best you can be, but do it for you. The way you talk, the things that you own, and what other people think of you doesn't affect who you are. It's what YOU think about yourself and how YOU feel about yourself that makes you the person you are.
Accept who you are. Don't strive to be like someone else. You are an individual. Don't allow others to change the essential you. If you don't like your life then change it. If you don't like the way you look, then change it. But do it because you want or need to become a better person, not to conform to other people's opinions, or to fit into the crowd or stand out. Change has to come from inside and it starts with YOU.
Value who you are. If you undervalue yourself then others will too. Accept that you have good qualities. Don't compare yourself to others - we are all different. Learn to love yourself unconditionally. You are unique and there will never be anyone else like you in this world.