be mindful of when you are stuck. when a hard problem makes you walk away from it (it isn't easy to realize when you do, it requires practice), write the problem down. write the first small thing that you need to figure out to start figuring out the larger problem.
unfuzzy the fuzziness.
I often find after writing something, I'm taking lots of half-formed thoughts that were keeping my brain occupied and relieving myself of the burden of carrying them around and keeping my thoughts on an issue sorted out. It's kind of liberating and it let's me properly turn my attention to something else and focus properly on it.
First step is to get it all down in some persistent form. Second step is to iterate: organize, clarify, simplify, expand, etc.
Once you explore all of the edges while writing/taking things through, you often find what you were overlooking before.
Same for why teaching works to increase the knowledge of the teacher.
I like to write things I'm learning about as if I were teaching someone less experienced than I was.