Michelle Trachtenberg knows a thing or two about looking camera-ready — the 24-year-old has been starring in films since she was only 11 years old (remember her in Harriet the Spy?). So it seemed only natural when Crest approached the Gossip Girl and Mercy star about becoming their newest Crest 3D White spokesperson. “Seeing a bright smile is like a light switch,” Michelle tells OK!. “It can be very sexy.” And what better way to highlight those pearly whites than with spring’s hottest — and most versatile — lipstick trend: nude. Here, Michelle shows how to wear it two ways: sweet and chic for day, or dramatic and sexy for night.