Simple Testing – Add, Edit & Delete
By following the Add, Edit & Delete principle, you cover many bases such as data loss when saving and usability.
Once you've got these basics covered, then you think about other tests to widen the coverage such as: validation (positives & negatives) and boundaries. See my checklists for other tests.
This approach is particularly useful in agile where full functional requirements might not be available, However, this is just as effective for waterfall development.