For all of you who love being in front of a camera, or love the idea of modeling, or just want to feel like one...here is the number one thing you need to do: smile with your eyes. That means, putting your personality, energy, feeling, everything you want to portray out through your eyes. Make your eyes show what you want the people around you to percieve. Practice in front of a mirror if you have to. If you want to portray "sexy" then think of things that seem sexy to you and try to put that essence into your eyes.
If you are feeling self-conscious, the camera and everyone around you will pick up those vibes. So be confident and show it.