Your hair is still thick and youthful, but now is the time to get your color in check. "Many women in their 30s find that their natural hair color starts to get a little dull, so add subtle highlights to soften your face and skin tone," said Maldonado. "Using a deep conditioning mask once a week, like Frederic Fekkai's RX Anti-Breakage Treatment ($30; fekkai.com), will keep your strands looking fresh and shiny," added Gwyneth Paltrow's hairstylist Adir Abergel.