Painting with light
A method I like to use while I’m about mid-way through a painting is to duplicate all the layers to my file. Then I collapse all these layers into a complete image that’s flattened, and copy this flatten layer and darken it between 30 and 50 per cent. What this does is enable you to erase with light. Because the bottomthan the layertop layeris lighteryou can effectively paint with light, by erasing areas you want to be hit by a light source.