Currently, I am modulating the subsurface color chip on the PrincipledBSDF with a CombineRGB node connect to a texture node loaded with a base texture, no makeup, major blemishes, or tattoos. I plug the map into the red channel to represent a subdermal layer. The other remaining 2 channels can be used to tweak the color further for some interesting effects. I find it easier than to color pick the chip. Add a Bright/Contrast node for more variety.