For this image, I added two new (regular) layers and put them on top of the original. One I set to overlay mode, and painted in some pink/red highlights on the cheeks, bridge of the nose, chin, and forehead, then lowered the opacity until it looked good. I also added a small white gloss layer to the lips.Your final layers look like this:The original on the bottom, your two tweak layers, and one adjustment layer for every item you colorized.Your image is now fully colorized. If any colors look off, simply go back into the curves and change them. I would suggest leaving it for a couple hours, and then coming back to it for some more editing. It's amazing how your perception can change once you haven't been staring at it for a while. It's also good to get some outside opinions.Done at last...