Textures:
For the texture painting I used SimpleBrush combined with different alphas and Colorized Spray as stroke type. I started with a neutral and very light skin tone and I added different tones with a very light pressure (about 3-4 on RBG Intensity). I slowly added different spots and colors like I was painting in transparent layers of color.
Here you can check the texture without the correct shader and light yet:
Skin Shaders:
For the skin shader I used Sokar's solution and changed some parameters to try to improve even more on this already amazing shader. This shader is based on ColorizerTrishader and works pretty well in the skin simulation tones, faking some sort of subsurface scattering appearance. If is your intention to mimic this material for your own study using the screen shot below, please pay attention into the diffuse curves . To make this shader to work properly you need to set up very high values to the
diffuse curves on channels S2, S3 and S4. This will cause your model to appear very self illuminated in the view port but don't worry because after you hit the render button everything will be fine ;)
After you conclude the creation of the main skin shader using the parameters above (or importing the skin shaders you just downloaded from this page) you need to copy this shader to another channels. To do so, just click over the material you just created and click on CopyMat button. Now click on the next material slot and click on PasteMat. Repeat this step for the next 4 slots.
Now that you have 5 identical materials you can start to adjust one by one, adding a little bit more of specular in the second one, even more in the third one, fourth one, fifth one. Now you have a library with 5 similar materials different just in the amount of specularity.
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