Turns out your mother was right. "The most important thing in your 20s is to wear sun protection," says Kellett. You might feel throwing caution to the wind on a glorious sunny day, but you should use a product with an SPF of 30 or higher, she says. If you are still suffering from post-adolescence acne (a common occurence), choose a clear spray sunblock, which will be less likely to cause breakouts. In addition to your regular cleansing-and-moisturizing regime, Kellett suggests using a Vitamin C serum daily, for skin brightening and collagen production. Just make sure the product has a strength of 35 per cent or higher. ("One that's mixed by a pharmacist will be stronger," says Kellett.)