Back way back I used to put noise on my textures to give the illusion of blueness under the skin. From time to time I use blue instead of warm color setting with RealSkinShader. Try also maybe making the lips more warmer or putting some little blush on the cheeks to emphasis the translucency. This image looks washed out with too bright light maybe. I use a couple bluish and greenish spot lights not too bright. I don't know if your specular is too high but sometimes you want that so... Darkening and texturing the eye socket below the eye also gives both contrast and the illusion of thinner pigmentation in the skin... these are old painters tricks... contrast contrast contrast. Warm skin against cold hair and cold skin against warm hair, the problem in pigment painting is punching contrast given the limitations of the materials.