Cigarette smoke breaks down the vitamin C in the skin, which can cause premature wrinkling. Furthermore, nicotine causes the small blood vessels and capillaries in your face to contract. This affects circulation, and deprives the skin of nutrients.
If you are a smoker concerned about premature wrinkling, the best thing to do is cut down on smoking or quit entirely. If this is not an option, make sure you eat healthy foods, drink lots of water and take additional care of your skin.