About the pic you mention, the retoucher (using Photoshop):
1. Didn't move any part of the photo to have a better shot. I mean, the eyes are in the same position, they aren't closer, the eyebrows are the same, the hair it's the same, so first thing if you want a retouch like this: Leave everything as you find it
2. The hat, if you place a white layer over the background and change the blending mode to SOFT LIGHT. Then you have the same finished hat. Mask everything except the skin. As you can see, the hair and most of the shadows have now the same shade than the finished picture, so, You are almost there
3. The skin, use the healing brush to remove every detail that you don't wish to have in the finished pic. In the eye bags, the finished picture it's not very reallistic, it seems to have a soft regular brush with purple or brown color, but you can't see the pore of the skin that much, so don't worry.
4. The skin's shadows, for this it's a little more complicated but not that much, use a new white layer but make a mask copying the blue or green layer.
5. The eye's whites are just dodged, use dodge/burn tool.
6. Use the curves, leves, selective color or what ever you want to have some last adjustments.
Ok, I was very technique on this answer, but if you don't understand or want a bigger explanation on some step, please ask