I like this approach, I tend to do similar things, particularly marking cells to be filled in, and I also tend to choose pastel yellow for this. If there are different users / departments then I use some kind of colour code to indicate who puts what where (a bit like the “office use only” bit at the bottom of a paper form). Cells for data entry I would usually put validation on as well, if a simple ruleset exists.

I also use simple error indicators, such as a ! next to invalid cells and then a check cell at the top which looks for any errors and puts a big red banner across the whole screen screaming “something is wrong! check your data entry” (actually usually wording a bit more helpful than that). I have used conditional formatting to make the shading of entry cells clear once all cells have a valid (and hopefully correct) entry in them. This makes much cleaner printed versions if needed.

I have had couple of cases where one cell’s entry makes a big difference to the whole of the rest of a sheet, for example choosing a currency for an expenses claim form. In this case I used conditional formatting to colour the entry cells differently depending on what units they were in to make it really obvious. I changed the labels as well of course to give the right prompt.

Keep up the great blog!

I actually prefer (sometimes) having summary formulas at the top of a sheet with the heavy duty calculation further down for reference if needed.

For one client, one sheet would never work (SpreadsheetStyle suggestion). 4 pages of detailed input, with 35+ pages of calculations, and 10 summary views. Complicated problems require a lot of detail for clients that want to be able to follow the entire calculation process. The challenge then becomes one of making it easy for calculations to be followed.

I agree with the suggests you list here and on the links, but alas, clients have much different ideas.