In Your 40s

Thanks to technological advances, at-home skin-care tools can now help prolong the results of pricey in-office procedures. "Using a blue light device is a great way for patients undergoing photodynamic therapy sessions, which is used for acne treatment as well as to reverse photoaging, to continue to kill acne-causing bacteria on their own," explains Friedman.

Tria Be Clear Skin Clarifying System, $295; nordstrom.com