Reposted from the Daily Thought thread for easy reference. General, useful advice for community site building.

1. Identify the specific differences and commonalities of experience that you feel are important to focus on - what is the community need you are serving? Eg, "brand" your site with clear identification and focus so you can attract the user base that would benefit most.

2. Clearly communicate those differences (your "brand identity") in a way that is easy to understand, but that does not insult or denigrate people who do not share those differences. It just is what it is, and it serves the needs of a specific segment of the community. The fewer words you can summarize this in, the better. Try for a positive statement rather than a negative one, eg, defining what your brand is by identifying what it DOES do rather than by what it doesn't do.

3. Identify ways to keep your community on track and on topic while remaining positive, professional and respectful of different needs even if your site can not directly support them. An example of this would be our Otherkin and Vampire FAQs, which offer cross-community courtesy and useful links while making it clear that Werelist does focus on therianthropy and must respectfully refer people with different support needs to other sites.

4. Cover your ass. You WILL eventually have to deal with trolls, spammers, vandals, underage folks to whom COPPA and other laws apply, member conflicts that you must act to resolve, people posting illegal download links and possibly worse. By worse I mean the really bad stuff that can put your site owners/admins at legal risk. Have site safety protocols worked out proactively so these issues can be dealt with as smoothly as possible without negatively impacting your community.

Limiting the community you serve to a specific subset of shared commonality or shared experience is not a negative thing by any means, not when a positive communication and support network is maintained between community groups with free flowing mutual referrals. If a specific need is not well met in X place, then X can cheerfully point folks over to Y or Z, and vice versa. Folks settle where they are most comfy and their specific subset of needs can be best met, and everybody wins.

You can definitely achieve your "brand identity" and clear separation/identification of the specific community subset whose needs you are focusing on in a completely positive way, without any negativity and with mutual respect and cooperation with sites that serve different needs. Stay focused on the good stuff - the specific needs you want to serve - and worry much less about defining what you don't or can't do. That should fall more naturally into place once the positive things are clearly defined.