Ask what the image is about
Identify the one detail viewers should notice first. Trim bright objects, empty edges, or partial figures that compete with it. Small removals often have more impact than an extremely tight crop.
Use space intentionally
A centered subject can feel direct and formal. Off-center placement can add movement, especially when a person looks into open space. Horizons and strong lines should appear deliberate rather than almost level or awkwardly cut.
Do not crop away necessary context
Environment can explain scale, place, or emotion. Compare several frames and check the final image at normal viewing size. Leave enough pixels for the destination, and retain the original so the composition can be revisited.