Yeah, finding something good can take forever! Honestly I can't say I looked too hard for that picture, but I quickly skimmed through a couple hundred pics probably. This is something I didn't anticipate doing when I started playing around with the image, but I started really getting into it mainly to see what I could do, and secondly for some masturbation material.
If you want to work with what you got, you can try the following (and it's going to look like shit at first and take a ton of touch up work to look decent, but something to play with):
I hope you have the nude on a separate layer, it'll make adjusting it much easier
1) Take the nude, make a copy of it.
2) Set the copy to grayscale (Image>Adjustments>Black & White)
3) Invert the B&W (Image>Adjustments>Invert)
Now your lights are dark and your darks are light on the grayscale.
4) Get the marquee selection of your B&W&I layer. Ctrl+Click on the layer's little preview in the layer window. That should select the data in the layer.
5) Make a new layer, keeping the selection.
6) Add a mask to the new layer via the selection. To add a mask, click the gray square with the white circle on it at the bottom of the layer window
7) Color anything you want on that new layer from step 5. I'd recommend doing an initial fill with a peach color skin tone sampled from the original body.
8) Set the layer's Blending Mode to "Overlay"
Now you should have something approaching a consistent lighting and skin tone. Now you'll have to smooth things out, add color to the nipples, do any edge blending etc.
EDIT: I see Urgoslav beat me to the punch. Can you share your technique?
Edit 2: Added step by step. Nipples are the most off thing because they're not nipple colored and they're inverted.