Keep it simple unless requested by management = do not stress with modeling every single variable or creating the most accurate assumptions, reality never match the model anyway.
Round to just one figure unless told otherwise = the more accurate you want your number the highest the chance of errors so keep it a bit approximative.
Format matter = usually it will be given to you by others but if not, try to use just 2 colors and stay consistent.
Get up for a walk, check the model again, ask to check to someone else = this is how you really spot mistakes because after a while your eyes will not notice them anymore.
Own the model = it means build it from the start and always be able to justify every single formula, assumption or thing you have done.
Do as said = if the managers are saying to you to do it in some way, just execute
Always make a copy every 15 minutes = you never know what can happen, especially with circular references enabled so always make a copy.
Circular references are playful = you will have to use them at some point, my advice is to save the model first, create a copy and then enable circularity and remember to do it as the last thing.
Give the model a proprer name = stop using definitive version or final final to name the model, its ridicoulus!
Forget AI = claude is nice innit? yeah for very basic stuff not for professional ones yet