Gradation

In my ongoing series of rocks on the beach, the problem of creating a sense of distance was solved by the use of gradation.  On the beach, dark to light values kept the area receding.  The rocks on the right were painted lighter and lighter as they overlapped.  And within each rock, the values gradated from the top down to where the spray from the breaking waves softened them.  In the sky, the values gradated from a light midtone near the breaking surf upward to the distant sky. Not including a horizon line kept the attention on the focal area.

I also used gradation of color.  The warm central rock overlapped the next rock which included some blue, the next three rocks got progressively bluer as well as less textured.

Gradation exercises can be found in most instruction books.  Just remember to employ the technique where it's needed.