Today has been spent applying the finishing touches to Four's body. Using a texture sphere I transferred the texture I was working on to the main model and apart from what looks like an ambient occlusion anomaly under her belly, she's come out looking really nice.
I might modify the tinge of her tongue to add a bit of blue or orange. A way of giving it that alien vibe. Another factor is the tongue needs to be wet, It needs to glisten which could be done with a specular map as it shares its shader with the body..
There does appear to be a shadow under her eye when the cornea is included in the render. It could be it's reflecting the world, which is pitch-black as there is a 40% reflectivity value. If so, it might be gone when Four is put into an environment with more than directional lights.