To some degree, it's a matter of personal preference. When I was studying, I would write myself post-it reminders and stick them around my desk: "don't drop negative signs!" "write legibly!" etc. The act of writing it down and seeing it every time I sat down to study was helpful to me. But... this isn't the method I would recommend for everyone, because eventually your desk will look like this:



A much better way to do it - a way that will keep you organized when reviewing - is to keep a spreadsheet that you can organize by question type, topic, error type, etc.

I have detailed instructions for how to do this here: https://www.manhattanprep.com/gmat/blog ... -studying/