I usually don’t draw diagrams, but my mind works better with what I usually call “tiny examples”: working code unrelated to the main codebase. Most of the time I have pen and paper with me, but I never do anything fancy with it. The advantage of that is most of the times, when I’m done, I need only to copy the example to the actual codebase with small changes.

This process helps me in so many different ways, and seems so productive, but I’ve never found anybody that uses such an approach. I would love to discuss it further with other people so that I can improve it.