Drawing in pen and ink, I often rely on making dots to illustrate changing values into shades of grey. So I'm adding to my website gallery (under animals) a few older drawing-exercises that illustrate that. I occasionally add graphite which softens the harshness of black on a white background and tends to blend values even more.
But let me also share a drawing found a few years ago by a Montana artist, Bill O'Neill, now deceased. If you magnify the image, you can see the precise location of his "dots" to illustrate snow blowing, distant trees and more. No cheating with graphite. My hero!