Rapid Application Development / Advanced Excel Development

Inputs

• Never trust inputs
• Always test for correctness as soon as possible
• Limit inputs wherever possible (eg option buttons, or drop downs)
• Use data validation but be aware of its limits (easy to bypass and overwrite, must use circle invalid)
• Help users by clearly identifying what is needed
• Give clear feedback on errors or problems
• Minimise input - Let Excel do the work
• Have validation formulas nearby
• If test is ok say "ok" (or "Row/Column check ok") not "" (formulas that return an empty string often get overwritten by accident)
• Prefer Text in cells rather than comments
• Locate input cells where they are easy to find and an bad edit (eg delete cell instead of clear) will have an obvious, but not disastrous effect.
• Use worksheet protection if you need to but do not rely on it, and be aware of its limitations and annoyance factor.