Establish a focus point
Choose the detail that needs to be sharp and check it at a larger view. Then look at what happens in front of and behind it. Depth of field is useful when it supports the viewer's attention.
Control brightness deliberately
Compare a scene with bright and dark areas and decide which detail is essential. Use your camera's preview and histogram as aids, while judging whether the photograph preserves the intended light relationships.
Simplify the frame
Remove one distracting element by moving rather than cropping later. The exercise links camera position to composition and helps separate a strong subject from a strong photograph.