First open your image you want to be retouched.

Duplicate the layer. Now hit CTRL+U to bring the Hue/Saturation dialog up and add more saturation. I've added 40 to saturation. Put the layer on "Color" mode.

Now go to Select > Color range.

In the dialogue box use the color picker to add more to selection. Basically, you need to select the face. Don't worry if you can't select it perfectly, as you don't need to. Play with the color picker and Fuzziness, but beware that your selection do not affect the lips and the eyes or the hair.

Now with the elliptical (or rectangle marquee tool) right click on the selected area and choose Layer via copy. Now put this newly created layer on "normal" mode.

Now go to Filter > Blur > Gaussian Blur and give a quite big amount of radius. I've chosen a 8.8 one, but you should play with this value as it is depending on the resolution of your image. You're done: