This deep conditioning Kérastase Discipline Oleo Relax Anti-Frizz Mask ($62) can work de-frizzing miracles on thick, unruly hair as the rich cream softens with shorea butter as it seeps in. Plus, a little goes a long way: Oleo Relax products were discontinued a few years ago, so I stretched out what I had left as long as I could. Once I saw this mask return, I've never been without it.