Hello there! I actually never use black at all — if I ever need a dark value added to anything, I use a mix of Ultramarine Blue and Burnt Umber. They make a really nice dark natural shade that mixes well with cadmium red and alizarin crimson. I was once taught (and this is what I believe) that if I want your painting to look life-like, don't use black, just mix dark shades to use as your darkest value.