Generally speaking your skin reflects your lifestyle so the standard diet and exercise answer applies. Get more vitamins in your food by having more fruits and veggies, or at least try something like centrum if you haven't got time to eat properly. I find that exercise is really good for my skin as the sweat flushes out all the junk (plus the added benefit of feeling great overall
). And to make things complete maybe you can consider a good, nutritious moisturizer?