I use Obsidian with several thousand notes for everything "writing" (structured - studying, definitions, thinking things through, and unstructured - memorable moments, stories, people, random streams of thought). "Actionable" things (todo lists and tasks) have their own place. My motivation is quite similar - I feel like I just forget things. And it's been wonderful! It's so nice to write about a nice moment, and be reminded that it happened - small things you'd otherwise forget.
I've found ideas from Andy Matuschak extremely useful - https://notes.andymatuschak.org/About_these_notes?stackedNot...
On a practical level the crucial features of what's been working for me for a few years now (inspired by Obsidian community and Andy):
* Notes have to be very clearly "bounded" - break things into smallest logical "statement" units, and interconnect notes instead of having behemoth notes with everything in one place
* Note titles have to be an explicit "statement or sentence summary of the contents, with relevant context" - which really helps with search / discoverability. E.g. "Browsers are the most common and visually advanced applications that make use of the internet, but there are also many others" instead of "Web browsers" or "Applications that use the internet". Or "The day I embarassed myself at football". An alternative of this is to have explicitly clear headings.
* The idea of putting notes into a "reverse spaced repetition" algorithm where instead of spacing things you've learnt further and further into the future, you are spacing things that are "fruitful" nearer and nearer in the future (and when you have less to add, further into the future, when eventually a note becomes "evergreen"). You then have a "queue" (mine is always packed) of notes that are due, and you pick them up as you like. This can be achieved with https://github.com/st3v3nmw/obsidian-spaced-repetition and is described better by Andy: https://notes.andymatuschak.org/zJrfPCbY7GcpV9asEc8NTVzXTAV4...
With the above things combined, I usually sit down just to write and unload things from my mind and enter notes into the (basic) "attention algorithm". That way I never stress about polishing notes, and there's always a time in the future when I come back to a note written a long time ago, make some edits, maybe split it into a couple of notes, clarify the title, maybe merge a duplicate (if something has come to mind twice, it's clearly important to me!!). With explicit titles I almost immediately know what the note is about, trigger new connections (between the time I've written the note and now, some other relevant thing may have surfaced which changed what I think or know, or I've come up with a clearer way to describe the same thing).