I think by writing. This means that I wind up with vast quantities of notes and thoughts around anything I’m working on. Right now I’m doing a lot of work around the CSS Grid Layout and related specifications, and have created some detailed notes for myself about how various things work and interact with each other.
I’m going to start publishing these cheatsheets, as if I’m referring back to them they may be useful to someone else. The first is a comparison of how the Box Alignment properties work in CSS Grid Layout and Flexbox. Box Alignment is interesting. Each layout method defines slightly different behaviour as not all types of alignment are possible for each layout method. We have browser implementations of Box Alignment in Flexbox and Grid, and it has been useful to me to compare and contrast the two.
The cheatsheet itself is also laid out using CSS Grid Layout, until Grid lands in your browser of choice enable it to see the layout - although it looks fine without.
Take a look at the Box Alignment Cheatsheet.