Kérastase Elixir Ultime Oil Serum, $50, available at Sephora
Whether I let my hair dry naturally or dry it with heat, it's bound to get frizzy at some point in the day. I've tried an absurd amount of frizz creams and serums, but this is my favorite thus far. Since my hair gets greasy very quickly, I'm always a little hesitant of putting straight oil into it, but this lightweight formula adds shine without that greasy look. You can use it to protect hair against heat before a blow dry or to smooth your locks and minimize frizz on dry hair. Plus, it smells delightful.
I have naturally thin, wavy hair, but my waves can get pretty wonky, especially with humidity. If I wake up to a mess of these wonky, misshapen waves, I'll wet my dry hair from root to tip, run a few spritzes of this oil through it, and let it air dry — it takes a few more minutes than throwing on a hat, but it gives that just-hopped-out-of-the-shower look. — Remi Rosmarin, reporter