We did an AMA with Bill Johnston who is the Chief Community Officer at Structure3C where they help companies like Intuit, Salesforce, etc.
His two cents when we asked how would he go about building a community and bring the first 100 users.
The caveat to this answer (and anything else I say here) is that absent a specific context/application, my response risks being too general. So with the caveat of “It depends, but…”
The first step before thinking about hosting any community is deciding on a primary purpose or intention - why are you trying to attract and build this community? For whom? How does your purpose or intention align with your potential members? And most importantly: how, specifically, are you going to help members make progress towards their purpose and related goals over time?
When I say “attraction, rather than promotion” - it really comes down to have an articulated purpose, or intention, that attracts people to the community, vs needing an elaborate or heavy-handed recruitment strategy. Attraction doesn’t mean leaning back and waiting for people to show up. It means to get your purpose out into the world through your presence, content, and invitation in various forms.
Find the 5-10 people most passionate about your purpose. Do they already have a home? How can yours be better? Find out. Internalize. Evolve. Have your core find 5-10 more. Talk about what you are doing, shine a bright light on it. If it resonates, it will attract the right people who are motivated by the purpose of the community and are willing to take action.
If you want to see an example of this playing out in real-time, check out the community springing up around Roam Research (think Evernote + knowledge graph) and the #roamcult.
You can spend 5 minutes and read the entire interview here.
getting those first few can be hard, but, that's all you need.