Speaking of black and white illustrations, let's talk about black and white in general, and of course we are talking about 2-dimensional black and white. When I was in college it was sometimes referred to as "graphics", or "graphic arts", actually!
One way to address black and white art is to think of etchings, and of woodcuts in particular, for now. Woodcuts are often implemented in a soft pine board, (medium-size, for the sake of handling) with special woodcutting knives, or tools. Sometimes people draw on the board first, to indicate where they want to cut, or remove, material. To remove material (wood) creates the area(s) which will become white, in the print-out. Sometimes people paint first - usually black - onto the pine board, and this will become the indication of where to leave the wood alone, as it represents where the artist wants the black to remain.
Other times, a person will simply start cutting, with one or more tools, and after a while, will take a print, to see how it's coming along: sort of a "from the gut" approach, for black and white.