What makes a good spreadsheet? Two things: good design and good data.
This may sound obvious, but it’s all too easy to dive into creating a spreadsheet without putting much thought into its design. And a poorly designed spreadsheet is bound to make it harder to enter valid data. Without valid data, your spreadsheet will never yield useful results.
Good design doesn’t mean making your spreadsheet look good – although spreadsheet appearance can definitely aid in usability and readability. Good spreadsheet design consists of organising your data logically and ensuring that all your formulae are correct.