How do you build strong online communities?

The recent history of social media has made me interested in the factors that make online communities successful/healthy, or toxic etc.. This is one of the appeals of Tildes for me. I'm also emotionally invested in seeing a healthy future for the Irish language, which has seen some interesting developments in the internet age but remains in a precarious position as a community language in the country. You can see how these two interests dovetail together. At the moment this is a thought experiment, but later, who knows...

Tips I've got so far:

I've heard that some barriers to entry can increase group loyalty by making members feels slightly "invested" by earning a place in the community

I've also noted that some of the most persistant subcultures operate online but also have a strong in-person element (eg: furries)

There's also the common observation that good moderation is crucial to user experience and therefore group cohesion

Then I got some pointers from the Tildes docs:

• Trust by default, punish abusers
• Focus on user experience, not growth metrics
• Favour deep engagement over shallow/clickbait
• Empower members to make choices
• The golden rule (apply charitable interpretations, don't tolerate bad actors)

So, people of Tildes: what factors do you see as crucial to building and maintaining a strong cohesive online community?