When retouching a face (or skin in general), I'll first go through and get rid of blemishes & pimples etc. Things that aren't a part of a person face every day of their lives.
When it comes to things like wrinkles and eye bags, I will create a new layer, then use a healing and/or cloning tool to get rid of them. Once that is done, I'll adjust the opacity of the layer, so that they are still there, just less prominent.
Another layer will get an overall smoothing effect, selectively applied to the skin. And again, adjust opacity to taste.