Excessive sky or foreground (grass, concrete, pavement) should be cropped out equally.
Subject building(s) should typically be located in the vertical center of the image.
If a tree, column, or other element is significantly blocking the view of something important, it can often be omitted. When in doubt, ask a supervisor.
Trees should not be too big so that they obscure the view of the buildings or other important details. Shrubs should appear like they get trimmed every 2 weeks. We should only show large shrubs as an accent, or to soften a large, bare wall.