Gustave Courbet painted his dramatic self-portrait very early in his career. My copy (from an 81/2"x10" reproduction of the original painting), posted here, is on cardboard in oil paint. The original is astonishingly good--and also astonishing because apparently Johnny Depp has a look-alike in another time and place. (Great jumping off place for a science fiction story).
As general matter, I learned a lot by copying the work of others. This (finding something you liked and copying it in grays in the same size as the original) was an assignment in Ron Llanos' painting class at Art Center at Night. (If you're curious about Ron's critique, he thought it was okay, except for the whites of the eyes, which I made too white. He was absolutely correct. I didn't go back and change the painting, so the error is still visible.)