First, the brief backstory:
I'm looking to move from my current career in science education toward a career in UX/instructional design. As a part of this endeavor, I'm currently taking a class on online communities. I've joined the UX mastery community to learn more about UX (and also to deliberately experience an online community myself).
To get to your question:
I'm looking for information on either designing a site from scratch or using the right features available in existing environments. I'm interested in any resources that would be relevant.
What features of the design of an online site compels a user/learner want to join the community?
What features encourage the user/learner interact with other people?
Are there "best practices" when designing a shared user experience?