In the previous post I shared a new approach to quickly change skin color without making anything permanent (a lot of settings to tweak). Now I want to reveal a nice technique that will allow you to quickly improve the subject's skin. Such skin improvement removes major blemishes and wrinkles, smoothen the skin and makes the person look younger. In the image above you can see three stages of it (from left to right): original, 50% opacity, 100% opacity. This technique may not be perfect, but instead of doing "blemish by blemish removal" you can swipe them altogether. Anyway, I would recommend to correct those major ones first.
So, how to do it? Read on.

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The first step is to make a copy of the background layer (of your image) and apply Surface Blur (Filters, Blur, Surface Blur) as shown below:

This filter is often overlooked, but in our application it allows to smoothen the skin without significantly altering other areas (even with high radius). In my case I've set radius to 12 and threshold to 48. The threshold allows us to control how much the effect will be spilled into non-surface (edgy) areas. The result is somewhat seen in the preview window of the dialog above.

If you look closely at the skin after applying the filter it look plastic - no pores, no bumps, nothing. Nothing human I would say, more like a doll. And now we have to correct this by applying Noise and using the Median filter (in Filters, Noise):

• Apply Add Noise filter with settings: Radius ~ 1.5, Distribution: Gaussian, Monochromatic (checked)
• Apply Median filter with radius 2
• And add noise once more time: Radius ~ 0.5, with the same settings as above

These manipulations added little darker spots and "pore-looking" dots to make the skin look close to natural. Again, it's not a perfect result, but very close to one.

And the final step is to apply Layer Mask to make the effect visible only on the skin. I assume, you know how to do it. After that you may want to change the opacity of this layer to reduce the effect and let more skin imperfections show through.

Note: The application of the Surface Blur helps with a better transition of our skin into other areas, as well if you have shadows or glasses (like in my case) it will leave them untouched (or just slightly blurrier).