We tend to think of old hair as gray hair, but the years show up in other ways, too: thinning, dullness, coarser texture. So far, I’ve been hit only with the color change—and I intend to keep it that way. I treat my locks to Pantene Expert Collection AgeDefy Rejuvenating Hydration Masque ($13, pantene.com) a few times a week. It’s packed with three different silicones to strengthen and protect. I’ve also been impressed with Kérastase’s new Initialiste ($60, kerastase-usa.com), which contains essential fatty acids, ceramides, and green tea extract to fortify hair. Like a skin serum, it’s also meant to enhance the results of products applied over it. I like using it alone, actually, and it gets bonus points for preventing one hair woe that knows no age: rainy-day frizz.