Excerpt from this article, which is from 2007, but still provides a very good summary of community-building advice that we can all keep in mind:
Before we get started, first I want to rant a bit. I hate the term User Generated Content. I never use the phrase when talking about this stuff and I’ll never use it when writing about it. I consider it a pejorative that reveals a lot about the person saying it. It makes members of your site feel like dutiful robots, crapping content that you convert into cash. The proper (respectful) term is community, and running one is a real challenge. If you’re building a community you have to love what you’re doing and be the best member of it. It takes great care and patience to create a space others will share and you have to nurture it and reward your best contributors. It’s a decidedly human endeavor with few, if any, technical shortcuts. Ok, back to the tips.