We have some key categories of tags. While we can't actually organize tags into hierarchies, it still helps to think about them in groups. None of the examples in this answer are meant to be literal tag names (though some might be); this is about concepts.
Who: tags about the different constituents within a community, for whom there might be special needs or considerations: new users, established users, expert users, moderators, and, possibly, problem users and/or trolls.
What: (a) tags about the things people are trying to accomplish in a community: curating content, promoting/expanding a site, managing conflicting goals (site scope), migrating communities, shutting down communities. (b) tags about issues communities need to deal with: these will mostly be about behavior in some form, e.g. bullying.
Where: tags about the context of a community (if relevant): physical communities, email lists, specific platforms with their own broader rules and expectations (Stack Exchange, Reddit, Facebook, maybe others).
When: tags about lifecycle, when relevant -- new communities, maybe others.
How: tags about all the mechanics and processes needed in order to run a community: conflict resolution, guiding new users, establishing consensus, choosing (and moderating) leaders, disciplinary actions.
I skipped "why". That's the one aspect of this that really belongs in your community, not on a site about building communities.
Any given question will probably have tags from two or three of these buckets. That's good; a single tag isn't meant to fully describe or specify a question, and that's why we can use up to five. Think of any individual tag as one meaningful slice through the questions on our site, and the combination of tags on a question as more-fully applying to a specific set of questions.
