An online host (or community builder) should strive for "civil discourse". This takes a shared commitment on everyone's part to work toward better communication, and it requires a place where one builds "social capital" by contributing to the shared knowledge of the community. Good online discussions create a "gift economy for knowledge-sharing".

A host is like a host at a party, inviting a good mix of people, and getting them to talk together and enjoy themselves.  A host is also an authority, enforcing the rules and standards of the community, and setting a good example for how to contribute and behave. A host is also a "cybrarian", a keeper of the community's history and archives, who actively hunts down new resources. A host shares the stage with the community.

Communities cannot be designed from the top-down, but you can create the right conditions for them to emerge, and then grow them through "careful intervention." Establish a few clear rules, based on basic courtesy, at the beginning, but then let the community create additional ones as needed. The rules set at the beginning will affect the character of  the community for a long time. Natural leaders will emerge in the community, encourage and mentor them.

Be patient, and allow your emotions to defuse before responding to anything. Early mistakes have long term consequences, especially where trust and conflict are concerned. Being overly forceful will backfire, be persuasive instead. Build relationships with members, and welcome new ones. First impressions are critical. Make individuals feel acknowledged and valued from the very start, and point them to resources you think will be useful to them.

"Let the community co-create its own dramas, shared language, founding myth. These all must precede discussion of creating a social contract -- dramas that all witness and participate in, shared language, rituals, myths, jokes, customs are how people get to know and value one another enough to want to go to the trouble of creating a social contract."