Following are a set of pictures showing progress on a painting I'm currently working on:
"A" is the original photo I made of a scene in Joshua Tree National Park in California. I like the look of the place, but I think it could use a little more "oomph."
In "B," I've finished the sky (complete with a setting sun) and distant granite formations. The foreground is mostly blocked-in as well.
Now I'm at a point where I need to think about where to locate the foreground Joshua trees. Sometimes I'll locate objects exactly where they are in nature, but in this case, I wanted a more intriguing composition.
To help me with my composition before making the major commitment of painting over my hard-worked sky, I placed a sheet of glass over the painting (which is dry at this point) as you see in "C." (The glass is heavily scratched because I sometimes use this sheet as a palette, scrapping dried paint off with a single-edge razor blade). I paint some rough sketches of Joshua trees on the glass, scrapping off images I don't like, making adjustments until I think I see what I want.
Then I painted in the Joshua trees. In "D," the trees are blocked in, and I'll add details during the next painting session. Then all I should have to do is finish the foreground shrubbery, maybe add a critter of some kind, and I'll be done!
Composing an image is often a "no-duh," but sometimes a little help can be nice. It may already exist in a photo I'm using, or I may make a detailed pencil sketch or even a small painting so I can see it before working on the "real" piece. But this time, the old "paint on the glass" stunt seemed to do the trick!