I go against recommended practice and have different vaults for different things in my life. The academic note vault is separate from the personal vault is separate from the creative projects vault. I have also committed sacrilege by not having many notes linked to each other. I’m trying to migrate a lot of notes from Google Docs and Notion over into Obsidian, so all of the vaults are pretty messy.
I love the LaTeX integration. Lots of math formulas in the academic note vault. I use the callout feature everywhere. I also nest callouts in callouts. I’m frankly treating them as equivalent to toggles in Notion.
I most often go to the personal vault where I have a list of things I’ve 1) seen online before, 2) spent at least an hour trying to refind that thing later and 3) will probably want to find again. This way I don’t lose time trying to find it again. It’s really helpful for me. I also have a list of food brands and how much I liked them, so I can remember which brand of turkey was bad and which was tolerable and which I’d definitely buy again.
I run RPG games for my friends. I create a new vault for each adventure. I typically create document folders like: locations, npcs, objects, events, rules, notes.
For common stuff that I use in every adventure, I just copy those files and folders into the new vault from the most recent old vault (the rules folder, for example).
I love how lightweight and simple this is in Obsidian.
I use links where it makes sense to me, and I don't worry overly much about link counts or the graph view. (I use both, I just don't stress over it). The tool should work for me, not vice versa.
I don't use plug-ins, but I do use style sheets and game specific fonts. Autohotkey is also great for making repetitive and/or complicated formatting easier. Getting the fonts embedded into the first project was a technical nuisance, but now I just copy that into every new vault.
Watching YouTube videos made by Obsidian power users, I'm super impressed by the things some people do with it. But I prefer keeping my workflow fairly simple. If I spend too much time messing with the tool, that feels counterproductive to me.