Illustrator Andrew Loomis developed a practical scheme for organizing the tonal values of a picture.
In his book Creative Illustration he presents squares of four different tones: white, light gray, dark gray, and black.
If you let one of those tones dominate, you can arrange them four different ways: 1. Grays and black on white, 2. Black, white, and dark gray on light gray, 3. Black, white, light gray on dark gray, and 4. Grays and white on black.
Nearly any sort of picture can fit one of these plans. Loomis proves it by creating a set of thumbnail sketches where the tones are carefully grouped and simplified.
These sketches of a mother and a baby near a window follows the third plan. "So many of us attach so much to the material and subject, so little to the design and arrangement of it."
(a new republished edition will come out soon).