Next I selected a largh area around the eye and copied (Ctrl+C) it. I Pasted (Ctrl+V) it and created a new layer. I moved it to the eye area of the texture map and use Free Transform to scale, distore, and rotate it into position. Free Transform should be under Edit > Free Transform or Ctrl+T. What I'm aiming to get isn't the eye texture itself, but the eyelids and skin around it. I'm actually going to paint over the eye, pupil, etc. in a moment so don't worry about it being in place as much as the eyelid and skin
Using the eyedropper, I grabed a dark redish-brown from the shadow of the eyelid. On a new layer, I painted over the center of the eye UVs (the part from the inside eye socket) so that I'd cover up any white from the original eye photo
Use the eraser to soften the edges of the eye skin layer so that it blends better with the face skin layer under it. Use the smudge tool with a very large brush setting and strength around 50-60% to push and pull skin tone to different areas of the face that are still white. The main problem with using the smudge tool is that it smooths out any skin texture and we want the skin texture to remain intact as much as possible. So while this does get the colors and tones where we want them, it destroys the texture so we'll have to come back over it with more source in a moment
The 'RubberStamp' tool is actually very useful when doing texture work. Go to the layer that has the nose and mouth on it. While holding down Alt click on a section of the cheek that has very little shading. Now release the Alt key and click a little further away in a white area. It paints starting from where you clicked and held Alt.
It's a good idea to duplicate your image every now and then, delete the UV guide layer, flatten it and save it overtop of the texture you currently have applied to your model. When you go back into max, it should update the texture and you can see the progress of your texturing so far
Frequently, when I go to make adjustments on a photo layer, I'll actually duplicate that layer and work on the duplicate instead of the original. If whatever I do turns out good, then I'm fine, if I mess up, I can just delete that layer and I still have my orginal to go from again.
Duplicating layers is also handy for other things. On this I knew I wanted to be able to keey the eye lid photo layer seperate from the rest of the face for a bit longer, but I also wanted it down there for smudging and using the rubberstamp tool to continue the skin tone around more of the face. So I duplicated the eye area, merged one of them down onto the rest of the skin layer, but left the duplicate seperate and ontop. Now any smudging I do below won't show up since the part I care about is safely duplicated on top
I often turn the opacity down on my UV reference layer so I can see under it better. I also frequently just turn it off while I'm working on certain areas.
At this point I was getting ready to put in an ear, so I got some ear reference that was close enough to the skin tone that I could settle for it. First I just pasted it onto the texture without worry as to where it would go. The skintone match isn't perfect so I'm going to need to do some color adjusting to get it closer before I start to worry about blending things together and placement