Strike a pose

Kritikos says to put one hand on your hip, relax your shoulders and raise your chin slightly for a lean, slender look. Putting one foot slightly in front of the other and angling your body a bit (without slouching) will also help you look slimmer, says Bedder.

If it's possible, don't stand with your back against the wall, says Bedder. Try to give yourself at least a foot or two between you and your background so you don't get any weird shadows. It's also best to have the photographer stand at least a few feet away from you, holding the camera at chest-height.

Also, spend time practicing your pose in front of a mirror (trust me, celebs do it all the time -- that's why they always stand a certain way). Then when it's for real, you can relax, since you know your pose will rock.