Hi Stan. When painting black always mix a complimentary colour for your base coat. This is because you can't shade black if the base coat is already solid black. I use flesh mixed with black as a base coat. Then I can shadow with pure black and I add even more flesh or a bit of white to the base coat for my highlights. (I use vallejo acrlics)
White is the same way. You can't highlight if your base coat is already pure white so use an off white base coat.
Hope this makes sense Stan!
Good luck!!
Gary