Thank you for introducing me to the idea of the "Zettelkasten" - I'm "one of the 10,000" for that idea today.
That other comment gave a link to that "how to take smart notes" blog post, the HN comments were here: https://news.ycombinator.com/item?id=22341518
A thing to keep in mind: there are two schools of thought. Niklas Luhmann was an extremely productive German sociologist who used his index cards system in a particular way. One school of thought tries to use his system exactly, like explained in the book that blog post is about. Others think that Luhmann had to work like that because he was restricted to physical cards, now with digital tools we can make other choices and get similar effects. Both ways are referred to as "Zettelkasten method".
I also realized that the system really works for producing content, things like producing science papers. You need to put work in how you formulate notes, and in finding connections between them. Without a good reason to keep working with your Zettelkasten, there is a risk it'll just be a pile of notes.
Those are the things that I found most helpful on my recet foray into the Zettelkasten world. Could save you some time.
One thing my notebooks don’t have is structure and a system of referral. This makes it hard to reference previous ideas and concepts. In fact, I don’t because it’s so difficult - it’s just one big stream of consciousness. And it seems Zettelkasten does that!