Trail of White

The white of the paper is very important to the watercolorist. But so many times, the white shapes in a painting can be scattered, random and unorganized.  Some authors refer to these as "popcorn" whites.
With some planning, white shapes can be organized to lead the eye through the painting.

Keep in mind, too, that one white shape should be dominant, probably in the focal area.  Try to avoid leaving whites along the edge of the paper. 

In this painting of Boothbay Harbor, the trail of whites form a "T" composition which takes the viewer from the foreground to the background.