The key strategy for what you are trying to do is that:

1. You need to attract a critical mass of community members of high quality.

2. You need to be strict about moderating the community, to keep it from deteriorating into a Facebook type environment. This includes responding to "experts" on your forums who give bad advice.

If you can build a hub which attracts top-notch people in that niche, who interact and create a high level of value, even when you aren't on, then you will have success.

Also, don't focus on trying to monetize it. First, build a quality, critical mass of regular users. Then, as you discuss things, you can find demand for products/services that you can offer gently, without forcing it on them.