If you're insecure about a particular part of your body, don't put yourself under the pressure of getting naked at first. There's nothing wrong with keeping a few clothes on during early make out sessions: you can reveal yourself gradually to a lover, as you build trust. However, don't see this as a permanent solution: it's simply a step in the road to help you build up your confidence enough to get naked. You can rest assured that if a lover wants to have sex with you, they like what they see.
Again, this is a step along the road rather than ultimate solution, but some people find it's easier to be sexual if they get dressed up in sexy lingerie, or even wear a mask (think Venetian masked ball rather than George Bush). It may sound silly but clothes help us play roles, and acting as if you're sexually confident is one of the easiest ways to become sexually confident.
Exercise and healthy living don't just make you look better – you'll feel more emotionally resilient too. Better yet, exercise with your lover so you both benefit from pumping endorphins and extra stamina.