Wikilinks not Tags
The one organizational decision that changed how my Obsidian vault works: I categorize with wikilinks, not tags.
When I write about a Redis outage, I link to Redis. When I take notes on a conversation with someone, I link to their name. When I jot down a thought about a project, I link to the project's note. These are not references to other content — they are the category system. There's no separate taxonomy.
The reason is compounding. Tags are one-way: you attach a tag, and later you can find everything with that tag. Wikilinks are two-way. Every time I link to Salesforce, that note accrues another backlink. Open Salesforce six months later and there's a panel at the bottom showing every note that mentions it. I didn't maintain that list. It built itself.
Backlinks also give me what Luhmann's Zettelkasten promised — the ability to wander. I open a topic, see what's connected, and end up reading something I'd forgotten I'd written. Tags don't do that, because tags don't have pages.
The small cost is having to create a note for each category. The note is the category. If I want to put things under "Salesforce", I need a Salesforce.md. It can start empty, or have a paragraph of context, or embed a Base view of everything linked to it. I usually start empty and let it grow.
This pairs naturally with Bases over Frontmatter — once your notes are linked and have structured properties, you can query them like a database.