Hey L,
If you start from scratch again I would recommend masking the face, shirt and background in three different layers, then go like this:
Face: do a levels adjustment until you are satisfied with most of the skin, then after you find a patch of skin on the face with great color, use your clone stamp tool at probably 30-60 percent, then click the skin that is good and slowly clone that skin over the areas that are a little to bright. after that, adjust the opacity until it gets darker or if you want to, use the overlay option and it will overlay the skin keep in mind though that overlay may darken the skin too much so I would recommend either the pin light or linear light at around 11 percent.
shirt: this should just need a simple levels adjustment to bring back some of the details. Or another simple way of doing it is just duplicating the shirt layer and then going to overlay and it will darken the shirt. you may have to do it a couple of times. I believe a simple levels adjustment will do fine though.
background: I wouldn't do nothing to the background unless it's obvious that you worked on the face and shirt. If so another levels adjustment should bring it back to looking like it's an original shot. feel free to ask any questions.