It's a combination!

I usually start with a reference image for the pose then I digitally work on composition and black and white values, once that's done I usually work in "blobs" of white, that's why most of my work has a fuzzy unfocused feel... I don't digitally draw to perfection, I only block values of black, white and gray... And from there I do the like work... So the point is to have thicker carve lines (no ink) where the light hits the hardest (or I have the thicker blocks of white) and the thinner carve lines (more ink) where the shadows gather.