I used to wing Arduino and ESP-based projects - just pull out the breadboard and start plugging. As my projects got more complex, well I found myself simply giving up on a lot of them because I would lose myself.

I put a bit more project management into it now, I'll start with a Google Slide kind of explaining the problem I'm trying to solve and the abstract solutions, then I prototype electronics, then model an enclosure based on the prototype's form factor, print it, test-fit, and look for corrections to make, documenting everything along the way on photo/video.