I believe that having a clear purpose or aim for the community is crucial. It explains why individuals are participating and what they will gain from it.
We need to foster a welcoming climate in which everyone feels comfortable sharing and contributing. This includes setting clear guidelines and being friendly.
Definitely need commenting and upvoting for engagement. I'd also recommend features like user profiles, badges/achievements, and notification of replies to keep people coming back. Building a strong sense of community is key - maybe add forums or chat to foster discussions beyond just comments.