Most celebrities have their token photo pose, which they undoubtedly adopted in an attempt to combat those 10 pounds the camera adds [0], but how did they come up with the actual stance? The Sun has put together a list of ways to Look sexy in snaps like celebs [1] that offers a little behind the scenes advice for looking good in front of the camera. Highlights include [2]:

• The Over The Shoulder - Stars like Rihanna and Jenna Jameson (seen here) love the over-the-shoulder look because it's a statement pose and flaunts your back, bum and shoulders. It draws attention to detail of your gown if it's backless or really ornate.
• Cheerleader kick - Used by celebrities of all body types, a pointed and turned out toe pose adds an extra few inches to your leg, elongating its appearance.

For the rest of the list,

• Hands on Hips - This is Paris Hilton's token move. It's flattering because it makes your arm appear trimly toned and with the elbow pulled back it helps give you a bit of shape by drawing attention to your waist. Curvier celebs adopt the same pose but with their elbow straight out leaning their upper body away from the arm to give as much space between the two as possible.
• Shoulders back, stand tall - Eva Mendes is a fan of this less "posed" stance, which comes off as more natural than other poses. It draws attention to your décolletage and shoulders.
• Crossed ankles - Nicole Richie uses this one often to elongate her legs.

If you happen to be behind the camera, you can play with light and angles to make your subjects look thinner [2].

Source [3]