...but this week is Photoshop (before and after), correct? So for once I WILL be on topic, pretty cool, eh?!?
Believe it or not, I'm typically not much of a PSer (although after reading below, you may not agree with me...I have a feeling it's going to get wordy), I simply don't have the patience for it. However, with headshots I do need to work on them in order for the subject to look their best. So, I'm posting a SOOC and an after shot, along with the techniques I used for this image. I shoot jpeg.
SOOC (resized & sharpened for web only)

Fully retouched and cropped to an 8x10 ratio)

Ok, so this is my workflow on this one.
1. Almost every image is run through an action I made which runs noisweware on a very low setting, a defog, and it makes a levels layer for me (with no adjustments).
2. I did not need to adjust exposure at all, though much of the time I prefer skin tones a little brighter than how they were shot so I adjusted the middle slider in levels to about 1.10 or so, very slight.
3. Color balance layer, this shot needed just a bit more magenta in it and a little less green, I think shadows, midtones and highlights were adjusted on the green/magenta channel to about -2 each (see, I told you it was minor!) Be careful with color balance, it's easy to go overboard and then makes it tough to know what you did wrong and how to fix it.
4. Cloning. This is the tedious part. F had quite a few flyaway hairs that I didn't catch, so I had to go in and clone them out around and over her left eye and cheek. My fault entirely for not staying on top of the hair issue! I also cloned out a FEW skin imperfections and evened out the color of her lips - she had dry patches where her lipstick had adhered better than other parts. Lastly, I cloned out the little bit of the top of her right ear that was showing through her hair, as well as the dark spot where her earing hole is.
4. Eye enhancement. I do very little compared to some, and her eyes are naturally amazing (the camera caught all the wonderful detail in them) so there really wasn't much TO do! On this image I lightened the whites of her eyes just a teeny bit. Lassoed the whites, and brought down the saturation maybe to -4 and upped the lightness to probably about 10. Less in more in my opinion, I see so many images where the whites of the eyes are WHITE white, and that's not how they are in real life! I also minimized the darkness under her eyes slightly as well. Once again, for ME, I think less is more. I don't like it when the undereye area is all one tone. To do this I sample an area under the eye that is a good tone, then I brush it on "lighten" with a very soft brush at about 10% opacity over the areas that need lightening. The last thing I did was a very slight curves adjustment on her iris only to help a bit more contrast.
5. Softlight layer at about 15%
6. Portraiture. I LOVE this plug in. SERIOUSLY! I see images where it's been overdone and the skin looks plastic-like, but used correctly it just gives that final finish to the image. I try not to overdo it, but I know there have been times when I have. Still working on getting it perfect!
So, by now you're likely thinking, MAN, that's a lot of work. For this one it was, but only because of #4 - all the cloning. Had it not been for that, this image would have been processed in less than 5 minutes.
I do not do this for every headshot proof (nor do I do it for regular images), that would take a ridiculous amount of time! I'll fully edit one (occasionally two) files so the client can see what a finished image will look like. The rest of the proofs are uploaded to their gallery with only a quick color correction and sharpening for web. Once the client decides which image(s) they want, THEN I do a full retouching on it!