To create a clean, glowing canvas, Hollywood’s most in-demand makeup artists prep the faces of their famous clients with select skin care before applying cosmetics. We exclusively talked to five A-list artists —who work with everyone from Nicole Kidman, Beyoncé, Zendaya and Eiza González to Jessica Alba, Megan Fox, Sydney Sweeney and Mindy Kaling — about the tried-and-true skin care products and tools in their kits right now. “Getting ready for a red carpet or a big day takes preparation,” says Sir John, whose clients include Beyoncé, Zendaya, Serena Williams and Naomi Osaka. “I’m loving L’Oréal’s Midnight Serum. The formula is packed with antioxidants, so you wake up with a smooth, hydrated…