Color will make a form come forward or recede:
To make the planes in light or shadow retain their structure, maintain the value and change the color.
As you change planes (e.g., from slanted to upright) make sure your values separate.
Develop 5 compositions where you are satisfied with placement and value.
For each composition, introduce color on at least three planes.
Experiment with color shifts in the large masses to support the notion of recession.
Once your major planes read, begin to introduce more shape variety and experiment with accents and reflected light.
Oil or gouache paints.