Another one that I feel is important:

Identify the testable predictions that go along with your belief.

This not only wards off "just so stories" and confirmation bias; it also shows people how to mine their own knowledge to add weight for or against the belief you're offering. If their expertise overlaps yours at all, they probably have some knowledge to offer; if you point out the testable predictions your belief implies, they can deploy that knowledge to make yourself and them smarter.