Here is how it's done.
I have used the overlay blending trick many times and I have never really been completely satisfied with the results mainly because there is very little control over localized blending or effects. That is why I use blur. Yes the secret is blurring.
first correct the image for blemishes and any other irregularities. Smooth with the clone tool, color correct, anything. It doesnt even matter if you get unnaturally smooth like a porceline doll face because you are about to fix that. Once you do add a small amount of noise within a feathered selection around the face area. Be sure to leave out the eyes and anything else that doesnt have pores. Use just a small amount of noise at about 50%.
Now duplicate the repaired layer. Gausian blur until there is a subtle and soft lense effect over the entire picture. Easy, you can easily overdo this. Place this layer over the original at about 50% opacity (suit to taste). Now what you see is a blurred picture. Take the eraser with a highly feather brush using pressure sensing and erase around eyes and lids, mouth and facial lines such as the edge of the face etc. If the person is wearing rings or jewlry, that too. What you are doing is removing the blurred image to reveal the clarity of the layer below where you want clear crisp lines and sparkle. This leaves the entire image with a glamour look.
The other technique is the reverse. Place the clear layer on top of the blurred and erase the clear layer to reveal the blur below. I use this technique where there is large areas the I want to "paint" the blur onto (by erasing). It gives me more control that the first way. It is what I used with teresa.
Each has its own uses. Somes times I blur the face and the hair differently to get different effects but the erasing techniques remain the same.
Be sure to add a specular highlighed sparkle to the brilliant points of diamonds, eyes and such.
You will find this is a great way to correct old photos also. I used it with
http://www.texramp.net/~dcsas/nick
The entire lower layer was corrected severly. More so than you would normally do. What you are doing is really creating a painting pallet that your erase brush will use. I even colorize this overly blurred and corrected layer. Then I lay the original over the blurred layer and "paint" onto the original from the colorized, corrected layer below. You will find, after practice, that this gives you a artist paintbrush level control over the correction process which delivers much more sublety without the investment in meticulous masking.
Just another tip from Tex.