Once you figure out what smile style works best for you—Toothy grin? Close-mouthed smirk?—keep it from looking forced by lightly pressing your tongue to the back of your teeth. It will force your face to relax and make you look more natural. Also, if you’re posing for the paparazzi (or, you know, six friends with iPhones), don’t hold your smile through them all. Instead, drop it after each shot and switch it up.