What comes first? Forget the chicken and the egg, we're talking about our skin care products, like serum, moisturizer, face oil and sunscreen. A cabinet full of products to keep you blemish-, wrinkle- and sun spot-free means nothing if you don't know in what order to apply them. Instead of slapping them on and crossing our fingers, we conducted a skin care nerd-out session with board certified dermatologists Dendy Engelman, M.D., and Craig Kraffert, M.D., who is also the president of Korean skincare line Amarté. We grilled them to find out which products should be applied first, last and everywhere in between so that they can perform exactly as they're supposed to. Here, these derms school us in the exhaustive process of layering skin care.