Scott provides an example of composing with a limited vocabulary using a costal tree scene.
Limited vocabulary is another tool you can use to help you think about placement.
Use a limited vocabulary of shapes to begin designing a scene.
Use a variety of limited vocabulary shape sizes to get an initial placement of the major forms.
Assess the variety of your design in terms of shape, scale and proportion. Evaluate the variety of both positive and negative space. Unequal proportion of shape and scale helps in all good design.
Iteration is key to success ... do several compositions before selecting the one(s) you want to pursue.
Once you have selected a design for further development, refine the shapes with line to add interest.