From Social Patterns
Instead of creating a complicated empty scaffolding in hopes of enticing community to take root (the “if you build it they will come” fallacy), start small, compact, and then prepare to grow organically
Create one main topic, a pinned (permanently on top) welcome topic, and perhaps a separate help topic, and nothing else. Rresist the urge to anticipate the contours of the conversations and groups. Wait till people are begging for a subtopic, then fork the original group. Repeat.
This way, any pioneer community members will all interact in a single shared space, with no dilution of numbers. By the time they want to start sequestering topics from each other, you’ll have already reached critical mass.
Continue to resist calving off new groups until they are clearly and undeniably needed.
Sources / Similar Patterns in Other Libraries
example: Yahoo! Pattern Library