Amazing retouch,
Somethimes I did it for pictures and basically what I do is this:
1. I select some areas of the face (not eyes, not lips not, nose fills) just as if you were giving power retouch to your face.
2. Then I perfect the mask to feather the edges (be careful the feather gets natural)
3. Then I aplly Gaussian Blur (Try to make it natural too)
So it is everything, if you wanna get a more impressibe images, you can use the Dodge and burn tool to make the highlights and the shadows more pronounced,so your image will look with more contrast..., well that I usually make to make a model with perfect skin.
In lightroom there is and option to control the softness of the skin, sometimes it is amazing but sometimes it gives a gray tone...