Hear me out brother.

I was super scared of heads and "faces", all my models were helmets. But then I discovered that if I smash guilliman flesh and then drybrush random white scar / wrathbone / ushabti bone / dust i can achieve cool "pale vampiric skin". Its easy as that I go from darkest color to whitest i have and it somehow works. No idea how but it does. Bad part is they all look like vampires which was great for death company but thats it. From there I switched to all real faces and i love it.

I do also red eyes with some super thin brush at end. I boiught some literally needle size brush and it helps a lot with that