My general rule that I try to follow with judgment, besides trying to avoid it, is when I am aware of a decision someone has made that seems really stupid to me, I try to remember that I don't know all the facts, feelings, history or anything else that went into their decision. I try to think only of what I would like to think I would have done, based on what I actually do know about the situation, but accepting that I don't know everything.
It struck me in Meeting last week, that I should take the same approach to forgiveness. I can forgive someone more easily if I assume I don't know why they did to me what they did to upset me. And funny how often it seems worse once they try to explain it.