Every time I try to make a map, I force myself to try planning it beforehand instead of building away willy-nilly. And every time, sooner or later, I sit in front of a stack of badly hand-drawn maps and am out of ideas. Stuff I draw doesn't fit, doesn't work, I had a better idea afterwards, the proportions are off, the page is too full… you name it.
I tried different approaches. Floor plan design software, for one, though it's tough to find any that is free, works offline or without an account, and lets you save in some useful format.
So last night, I thought: what about writing?
I know I can do that, so what if I wrote descriptions of the maps I wanted to do? It can only get better, compared to drawing and sketching...
In fact, writing down ideas is always a good thing to do as it helps preventing you from forgetting about it, and even if it gets unused in your current project it can be archived in an "idea bucket" where you can come back to later on to reuse ideas for new/other projects.
Myself, I like to do a combination. I start out writing down the main ideas and keywords etc I have for a project, and try to write a story of what I want to happen in the project, and sketch out things I have a visual idea for to help remembering it and to start fleshing out details I didn't think of first.
example
The documentation would be divided up into segments with the occasional rough sketch of the layout.