There is a technique I sometimes use to repress detail on problem skin. I make a duplicate layer of a portrait, introduce a gaussian blur at 28.5 pixels, hit the quick mask icon at the bottom of the layer menu box and then use a paintbrush, set to 20% opacity to brush in a softness to the image. The benefit of this very simple method is that I can use the opacity slider in the layers panel to pull back on the effect. I try to be judicious when I use this method because I think most people's eyes are very good at seeing this "deception."
I try not to use any blurring techniques for most portraits. It really all depends on the skin quality and the way a portrait is lit. Contrasty lighting can make even the nicest skin look worse. Clients with big pores or rough skin texture love the softening effect and, when the images are for their use, I am not disinclined to please them. When I photograph for myself though I am too keenly aware that the introduction of the softening technique diminishes the value I find for myself in prints and images. I can only conjecture the same is true for my intended audience for these sorts of portraits = VSL readers and others who appreciate photographs.
The image above uses no post processing blur technique but takes advantage of a close, large diffuser to moderate the transitions between highlights, midtones and shadow areas. In this regard shooting with 14 bit raw files is helpful to prevent even slight banding in shadow areas and transition areas by dint of throwing more information into the mapping mix. That my model is young, has great skin, and has used make up well, is a big benefit to the final image as I pre-visualized it. (Actually, I can only pre-visualize in giant swaths, like putting up a big fence. Everything creative happens unconsciously in smaller sections of the big fence, mental ranch).
One uses retouching on images when there are details that take attention away from the main goal, a subjective but positive rendering of the subject in it's holistic form. At times one must "kill" the details so the whole construct can serve its purpose.
The right lens can also help. I am doing more and more research into why various lenses were designed to function the way that they are. I started getting interested when I discovered that the lenses that made the best black and white images for me were one with under corrected spherical aberrations. Those would include the 135mm f2.0 I recently picked up, as well as the raft of 105mm f2.5 Nikons I've been collecting.
There is a similarity between them which is a signature of sorts. Stopped down they rival anything out there for sharpness but at the wider apertures they create out of focus backgrounds that have a very pleasing aesthetic look. I know that the current mania, at least in the U.S., is to value a lens based on its ultimate sharpness. As I get more experience under my belt, and shoot more portraits, I'm beginning to think there are other considerations in lens design (and performance) that are equally, if not more, important.
My friends wonder sometimes why I seem to have a preference for older optics. It's not that I want the burden of manually focusing these lenses, it's that they render photographs of things in a way that seems both more pleasing and more real to me.....regardless of which camera I use them on.
Besides, if everyone photographs with the same little trio of zoom lenses then visual life gets boring.