Continuing work on the base layer, I decided the overall appearance was getting too pink in hue. To remedy this, I went in to the 'hue/saturation' window and slid the hue bar closer to yellow.

The ear was quickly defined by using the same light and dark skin tones I started the texture with. These initial hues are more to the magenta end of the spectrum, and since I just ran the base layer closer to yellow, it will make for some subtle variation.

Other areas of the texture were lightened by using the light skin tone- mainly on the jawline and eye sockets. The jaw was reading as too dark and saturated (probably from the previous levels adjustment), and the eye was reading like my dude just got dealt a 'shiner.' These areas were painted over with the airbrush set to a low (5-10%) opacity, as to allow old color to show through for more richness.

After stepping back from the monitor and noticing that the texture was consisting predominantly of reds and yellows, I decided to briefly stray from keeping it relative. I ran up a light olive green color, and began adding it to some of the receded areas, using the air brush set to a low opactiy, and blending it in further with the smudge tool afterwards. Areas to note are the jaw, the front of the neck, the base of the skull at the back of the head, the inner ear, under the center of the nose, under the brow between the eyesoket and nose, the nostril, and just over the top of the upper eyelid.

The lips received a bit more attention: I defined the bottom of the lower lip with a stroke of the light skin tone. The same was done to the top of the upper lip, to define where that form changes curve from the lip to the face.

A new layer was made on top of the base layer I had been working on! With the polygonal lasso tool (no feathering), I outlined the shape of the upper lip and filled it 100% opacity with a dark and saturated red. This layer was set to multiply, and the opacity of the layer set very low, as to just slightly darken the upper lip to give the illusion that it recedes into the mouth. This also makes a handy selection layer for later on, in case you are doing work around the upper lip and don't want to effect it (inverse selection!).

The inside of the nostril was painted up a bit with the light skin tone, to make it appear that it recedes up into the skull.

Further smudging was done over the whole texture to further enhance form as I saw fit.