We get schooled in customizing skincare by Valérie Grandury, founder of organic skincare brand Odacité. Lesson 1. Thanks to pollution, stress and hormones, skin is always changing. So should your skincare. “There’s no such thing as one product treats all,” says Parisian-born Grandury, whose 18 mix-and-match serums allow you to choose combinations for your skin type. Lesson 2. When in doubt, try the A-student of oils: wildcarrot-seed oil, which contains vitamins A, C and E and gives skin a healthy glow. Lesson 3. Oils, beauty’s MVP for 2015, coat skin to keep in moisture, but they don’t hydrate. That’s why Grandury launched her Odacité Oleosomes Time Release Delivery Crème ($75). Add two drops of serum to it or use it on its own. The cream contains oleosomes (energy stores found in oil-bearing plant seeds), hydrating hyaluronic acid and carrot-seed oil.