I have translated two photoshop skin retouching actions from Kent Christiansen and Chip Springer into a PhotoLine action (although simplified). The PhotoLine script can be downloaded here ( http://www.simplexx.net/actions/skinfix.actions ).
The action prepares a skin-repair layer, that has to be masked to restrict the effects to the skin only.
- Paint with black over the hair, eyes, mouth and the background (soft brush) on the white mask layer.
- Then adjust the opacity of the skin-repair group to 40%, as a starting point, an adjust to your liking.
The layers should be looking somewhat like this afterwards:

One example in two versions - original and skinfix with 40% opacity (original image thanks to chilombiano via morguefile.com):
