It happens to the best of us. You’re sitting in the hairdresser’s chair, black Velcro gown and all, wondering what foreign language the stylist is speaking as she rattles off complicated hair coloring terms about a major chemical process your scalp is about to endure. You could just smile and nod (like always) and leave your hair fate to the coloring gods, or you could consult our handy guide to make more informed decisions. Your choice.