The wall in sunlight; the shadows; the roof overhang. Light; middle; dark. I can name that tune in three layers.
Shape by shape, the painted version of the scene comes together as a series of layers. How many layers will it take to paint the door? The sky? The cobblestones?
Wherever possible, try to keep the whole page at a similar degree of completion, rather than bring one shape all the way to realization while the rest are still white paper.
Some parts of this scene require three layers, some only one or two. Keep it simple.
The shadow is the second or third layer of the road, depending how much of the joint lines you want to include. In either case, the shadow is painted on top of the lighter layers, rather than alongside them. If this doesn't make sense, send me an email!
Hmmm. This one might need 5 layers!