There really are no rules, so you can’t really do it wrong, but some things I have noticed in my graph:
Don’t tag because something “belongs” there, tag so you can find it. A tag is a context in which an item is useful. Otherwise you’ll end up with 100s of tags that don’t serve a purpose (been there, done that).
Use as little tags as possible (but not less)
Why the -t? If they are tags that belong together you can use #[[t/tags]] it will automatically create a hierarchy
When you start having more pages you start using queries to find things, having easy to type tags just makes life easier: {{query (and [[question]] [[logseq]] )} is just easier to type