When you started your first Discourse community, what did you find hard to do?

[codinghorror (Jeff Atwood)]

Partly intentional, though, as site owners tend to create too many categories:

Blog | Higher Logic

and

It’s Time We Talked About Tags

To start

Do categories scale?

No – you would use tags for that. Categories are like walls. Build 4 and you have a nice house; build 24 and you have a maze. Tags are much lighter weight structures than categories and more flexible.