I'm pretty sure it works very differently for different people so you have to figure out your own process. I've tried different things but at the end of the day, I simply have a notebook next to my laptop/in my laptop bag and write down everything in freeform text. No index, no bullet points and things like that. I put a date and start writing. I'll usually do some TODOs as checklists to get them out of my brain and bothering me at the start of the day but only big items, not each and every step. It's a mix of work and private things. Just writing stuff down is helpful for me, even if I never reference it again.

I do use the Feynman Technique if I come across something interesting and try to explain it on paper. So if I was using it just for work, I'd probably do that. Something like "Spec driven development (Github Spec Kit and similar toolkits) is essentially a bunch of md files that provide more context for agents. There are some scripts that provide scaffolding, having agents write the md uses a lot of tokens so writing them manually after the scaffold is generated makes more sense. Try with a small project."