I've been thinking a lot about what makes for a good group since I moved to Lemmy. Small and engaged is what I came up with, and authentic is definitely part of that. A lot of people's normal response is to look for the biggest group for everything, but I believe once a group passes a certain size it loses the ability to have good constructive discussions - at best you get a core group participating and a lot of people who just watch, but more often you lose the space for anything exept superficial conversations as everything that is not new gets lost in the volume.

It's a pity Lemmy does not allow for subgroups, as that would be a good option for larger groups. The best options I have come up with so far are including weekly themed posts, and ongoing posts for specific topics linked from the sidebar so they can be kept visible. I think moderating a group well involves being part librarian, not just the rules enforcement most people focus on.