Around your mid and late 20s, your skin starts to change and it's natural process of exfoliation starts to slow down, with fewer new cells producing. All that sun-exposure and late night partying lead to free radical damage, that has left your skin dull and your under-eye area dark and puffy. Try incorporating a moisturizer into your beauty regimen that includes at least SPF 30, like Neutrogena Oil-Free Moisture SPF 35 ($10), daily to help protect your skin from sun and environmental damage. Also try applying a vitamin-rich eye cream, like Olay Total Effects Anti-Aging Eye Treatment ($19), every night. Because the skin around your eyes is so thin, adding moisture can help prevent fine lines, wrinkles and dark circles.