Effects of gravity
Gravity has the perverse effect of pulling our faces down by one centimeter, on average, by our middles age.
Plastic surgery with no gravity
Armed with the knowledge of how skin ages in this world, we can perhaps extrapolate to imagine how we would look and age visually in space.
The effects of our genetics on skin will require manipulation of our genetic codes to produce more proteins and slow down skin death. That is still a while away, though not as long as you might think.
Environmental effects can be most easily controlled. Use of sunscreens and avoidance of noxious chemicals will lead to improved quality of the skin. Preventing the effects of ultraviolet rays will be of even more importance in the atmosphere-free environment of space. Then again, the windows on spacecraft and in space colonies can be made smaller to protect us inside. Proper climate control that allows for a constant and comfy humidity will also increase skin health.
The effects of gravity on our aging skin is a little more conjectural. If we discount how a child born in space would age (since that gets things too complicated), we can consider how a young adult in his or her mid-20s might age over the course of a lifetime away from the gravitational effects of Earth. Of course, any planet will have some gravity, but assuming our young astronauts are in a minimal-gravity environment, the effects of gravity pulling their skin down should be… minimal!
This may mean that while we continue to age physiologically to some extent, our appearance may hold its own better than on this planet. Our cheeks will be fuller, our jowls dissolved back into our strong jawlines, our noses more upturned and our necks smooth. All together, the prospect of aging in space does not bode well for cosmetic plastic surgeons!