Basically depending on the light source the skin tones will look different.
Skin colors come from pigment, so they don't change. So if your model looks a little more yellow or blue, then your light source is altering your perception of the skin tones. Just the same way that some colors change under a black light - the light source is changing, so the color only LOOKS like it is changing.
Doctors heal you, Artists immortalize you.
"Those who can, do. Those who can't, teach" - bullshit.
The usual staples for anatomy: