I usually paint my canvases a transparent color to start with. This eliminates the whiteness of the canvas and also provides an underpainting that I can leave showing in some places… should the mood strike me.

Some Randie Painting in Squid Row history:

http://squidrowcomics.com/lautrec/

http://squidrowcomics.com/choco-high-painting/

http://squidrowcomics.com/circle-paintings/

http://squidrowcomics.com/booth-wares/