In my case I’m just posting a lot to already-created communities found in the Lemmy directory that’ve got a chunk of subscribers.

If you’re going to start your own community for your own interest, I’d advise at least setting up on an already-populated Lemmy server (which you would have to be registered on) so it gets listed in the local directory.

If you’re going to host the Lemmy server and your community, I have no experience on that front/I would imagine there’s a lot of SEO and self-promotion you’d have to do to get it off the ground.