The mark making is done quickly and often just begins with a line that has no particular place to go. As Paul Klee said: "A drawing is simply a line going for a walk." And sometimes, there's a basic idea and the image is done in a very raw and crude way with no detail, the details are sketchy!
I like the images to be coarse and unpolished, unrefined and angry! I suppose they are simple contour drawings that show the outlines, shapes and edges of a scene, but they omit fine detail, surface texture, colour and tone.
I have filled a lot of little sketchbooks in this way. My favourites, although not good art paper, are the passport size Muji notebooks but I also use the classic Moleskine (14 x 9cm) ones too. Also, although I often use Rotring art pens, I prefer the cheap but brilliant Muji 0.38 gel pen.
The painting Oskar's Catalogued Dreaming started from a 3cm line drawing of Oskar my Maine Coon cat that was projected onto 100cm square plywood and filled in with acrylic and oilstick.
I have an idea for the baby image!