Find the key light
In most lighting setups there’s a key light (the brightest light source in the scene) and a fill light (less strong, but fills the overall image). In this painting I decide to make the sunlight (my key) only hit one part of the mountain instead of everywhere. It adds visual interest and draws the viewer’s eye to one particular part of the image.
Fore-, mid- and background
With less atmosphere near the camera, the darkest parts of the image will always be the most black nearest camera. I spend some time working out a few more details and making the foreground a bit darker, to help make it stand out against the lighter background. Clever layering should make it easy on the eye to take in the image.