How does smoking affect your skin?

Premature aging. Smoking causes damage to the skin in just the same way it causes damage to your lungs. Other than wrinkling due to puckering of the lips and squinting, chronic exposure reduces your wound healing mechanism, reduces blood flow to the skin, and alters your skin much like sun damage. There is also premature resorption of the bone, causing a flattening look.
Ages it. It dries it out, reduces its elasticity, increases wrinkles, lines and makes you look much older than your years.