Write one idea per note

A note should be about one thing, and its title should say what that thing is — ideally as a short claim, not a topic. "Write one idea per note" is a claim; "Note-taking" is a topic.

Small notes are easier to link to, because a link can point at exactly the idea it means rather than at a page that happens to mention it.

When a note starts covering two ideas, split it and link the halves.