Most of us know the rule of layering your skin care: in most cases it’s best to go from lightest to heaviest. But what about hair products? Does mousse come before oil? How about a heat protectant? Armed with a whole lot of questions, we tapped Mark Townsend, Dove celebrity stylist, to give us the lowdown on how to layer products into wet hair before you heat style or air-dry. While every hair type, texture, and style is different, there are some general rules that will allow you to get the best results.