Be confident on yourself!
Write down several positive affirmations to feel more confident. For example, "I am a smart and energetic student," or "I am a loving and caring girl who knows her friends' needs." Keep the list handy while you perform your daily visualizations.
If you are not confident about your look or body then let me tell you this:As a woman u need to learn love your body - Fall in love with your own body. Never make negative comments about your body and point out your faults to a guy. If your body is not up to speed, keep quiet and just start working out. Guys hate to hear you drone on about your body. It is a horrible turn off and then they will start noticing all the flaws you point out.
Go overboard to look absolutely fantastic every day, making the very most of what you have with clothing, smelling good.Stand up tall.
Then your confidence kicks in!

Good luck girl!