I was curious how to get the various hair colors so wanted to see what combinations did what 😀 I figured 1/10s would be fine enough for a test, though you can certainly do in between 😀
If you’re going for grey hair, I’d recommend 0.1 to 0.3 for the Melanin value and on the lower side of the redness. Save 0.0 in Melanin for albino or someone you want to have white hair.