jennifer lopez - scott barnesSara Jaye Weiss/StartraksPhoto

Jennifer Lopez‘s go-to makeup artist Scott Barnes just penned a how-to book, About Face, and naturally the superstar was on hand to fete its debut. We asked her to share the most important lesson Barnes has taught her. “Stay out the sun! He really nailed into my head. Bronzer and self-tanners are so worth it. Stay out of the booth, girls! And boys!” she said. “He’s taught me so much about contouring… what should be highlighted and what should be left alone.” But even J. Lo can’t have Barnes on hand at all times! “He teaches you how to do everything step by step so you can do it on you own,” she said of his new book. But if she guest stars on Glee will Barnes be coming on set? “You bet he will be!”

Joyann King, with reporting by Emma Oldenkamp