Anyone who has been in my painting classroom has seen that I usually have a bunch of half-finished paintings sitting around that were done in class to demonstrate assigned techniques. I just finished a 2 week class for high school students and have a new set of goofy unfinished paintings. All three are about 10 x 15 inches on gessoed paper.
The one above is a standard still life assignment, one layer of limited earth palette and then full color over top of that. Two elements on the left are the underpainting, right side has heavier coverage.
This painting started with full coverage in bright orange, green and violet. This strategy usually encourages more strategic color mixing later in the painting. I worked from recollection to commemorate a certain fisherman I know who has recently chosen white crocs as his riverside footwear of choice.
This is a rough and quick version of a technique that I believe (?) Titian used. I've read about it but am not 100% sure. At any rate, the theory is that he executed 1) a black line drawing on white ground 2) gray halfpaste over that with subtractive and additive rendering 3) full color glazing on top of that 4) another black and white rendering 5) continue to repeat the last 2 steps up to 16-20 layers becoming more subtle and refined each time. I made it up to 4 layers on the skin, fewer on various other areas. A few years ago I did a bunch of paintings with people standing outside with trash blowing over their heads- I enjoyed revisiting that subject.