When I was working in insurance from time to time I helped put together instruction manuals for our computer programs. It was hard because you had to assume they user had never touched a computer before, we stopped at how to turn on the machine, but it started with how to find the program and then open it and every little step from there.
Back in 1992 a friend taught me how to make the folded star Christmas ornament, I knew I would never remember how, and this was before the days of cel phone cameras (at least for me), so I wrote out each step and drew what I could and made samples of each step when the drawing wasn't making sense. Several people were able to use it. There may have been books some where, but we couldn't find it.
You really have to take your time and it was a great suggestion to re-read it after a day or 2 to look for omissions.