curling iron Credit: Courtesy of Sephora Hot tools are a major enemy to dry hair, and repeated use only dehydrates it further. We're not saying you need to ditch them altogether; just make sure you're using ones designed to lessen the damaging blow. Your best bet: A tool that lets you control the temperature. "You really only need something to be 390 to 400 degrees to get results, but some people turn their irons up to 450 degrees or worse, and that can really damage your hair," Hawkins says. The same goes for your blow dryer: avoid the urge to crank the buttons to the hottest setting. Spritzing strands with the Drybar Hot Toddy Heat Protectant Mist ($27, Sephora) before styling can also help prevent damage and lock in hydration.