Alternation of Values

 

Alternation creates a kind of checkerboard effect, only with a few more values.  The idea is to have each value shape border on two other values.  For example, look at the area on the porch.  Then look at the midtone and you will see that it will be bordered by a light and a dark.  Light, midtone, dark,
midtone, light.  You can also see alternation clearly in the rowboat.

I was first made aware of this approach by looking at the work of California style watercolorists, especially Rex Brandt and Robert E. Wood.  Study their paintings and you will see that what first appears simple is quite complex.