Good discussion for UNA.IO, too. My points would be similar to yours, Mark Purser :
1. Focus on one or two main features that facilitate your site function. Either discussion, or updates, or posts, or videos, but not all of them at once.
2. Be present and active on the site all the time to feel what's going on and how things work. That way you can find the right points of focus to improve.
3. Encourage original content and deep insightful discussions. The Internet is full of "quick share" sites and content for hyper-short memory-span people. There's space for such sites, but it's mostly occupied already.