I'm new here and I don't have a lot of experience on digital painting yet, so my question might be strange, but here is what bothers me.
I like to first make a grayscale shading and highlights layer and than add colors in an overlay layer above. I've noticed that when you add colors in overlay mode, above grayscale shading, the shades appear to be dead. I presume that is because overlay mode uses multiply on darker colors (below 50% gray) and shades become simply shifted down on brightness. I fix it by adding a copy of color layer in saturation blending mode above, and I also make a mask with inverted and more contrasted grayscale shading layer for that layer. That way shadows become more saturated, while highlights stay the same. I don't think that's the way it should be, but it makes the image look a lot better. Is there an easier way to fix shadows or maybe I'm doing it wrong altogether and there's no need to fix anything?