Hi,
I made a fully procedural skin shader that colors most important parts of face.
It´s using mostly geometry(normals/pointiness) and AO to generate colormaps of all the red, yellow and blue colors of facial skin. Shader includes details such micro-veins, pimples, darker dots and other imperfections. Also SSS reveals micro-veins under the skin. Glossyness is also defined by creases and cavities.
One color layer is made with a help of Empty box which you can easily adjust on any head size. It then uses mixed color ramps to and extra colors to chin, cheeks and skull coloring (blue, red, yellow) only on head area in case you want to use the shader for whole body.
I´m planning to add some other emptys to adjust masks for lips coloring and maybe even wringles.
I think I still need to make better bumpmap but otherwise it works quite well on any model.
model from turbosquid,
Albedo
Roughness/Bump
Albedo Layers
nodetree (still need to organize the rest of it and maybe some day build easily adjustable shadergroup)
rough color quide taken from the world wide web. Just to show what you should find from the shader.
