In any project based on community collaboration, friction is bound to develop. Skillful application of diplomacy and leadership help a community to work together smoothly, reducing conflict and encouraging people to contribute.
A catalyst knows when to Ignore all rules, and refrains from Wikilawyering even while using policy and guidelines as appropriate to guide others towards appropriate on-wiki behavior.
A catalyst encourages and motivates other editors. Showing courtesy breeds respect, respect fosters cooperation instead of personal attacks.
A catalyst is an active, but unobtrusive participant in discussions, keeping them moving, but not dominating them.
A catalyst is an example of our principles, leading others through carefully considered action.
A catalyst remembers that no matter what their role on the project, we all represent Wikipedia whether we realize it or not. Over time, if you are effective in the catalyst role, people will learn to follow your lead, so make sure you set the right example, and convey the right message to other participants. See meatball:RoleModel
A catalyst is cooperative, and understands that cooperation breeds consensus. A catalyst tries to get people involved in resolving problems cooperatively.