"Everyone sees your face before they get to know you or speak with you -- it's your first impression," says Jeannette Graf, M.D., assistant clinical professor of dermatology at Mount Sinai Medical Center in New York. And these A-listers make a beautiful impression. Julianne Moore, Penélope Cruz, and Renée Zellweger have skin so dewy and fresh they've become complexion icons. The key here is that they don't have sun damage, says Francesca Fusco, M.D., assistant clinical professor of dermatology at Mount Sinai School of Medicine in New York. "Sunscreen 24/7 is a must, even when indoors, in cars, and on planes where UVA comes through the windows." Celebs fight blocked pores and acne with in-office treatments like microdermabrasion, facials, and peels, and by keeping their hands off their flawless faces. "Don't cup your chin, and keep your hair out of your face, especially since styling products are a major aggravator of acne," says Dr. Graf. "And swab your phone regularly with an alcohol pad to clean off oil and makeup, since bacteria can be transferred to the skin."