Give yourself a cooling off period. Don’t approach a difficult person when you’re angry.
Don’t take the “hook” when people try to bring you into a conversation that you don’t want to have or aren’t ready to address. Simply say, “This isn’t a good time to talk about that.” Or, “We’ve gone over that before. You know my stand.”
Put your ego aside. Listen first. Often people just want to know someone has considered their point of view. You lose nothing but a few minutes by listening to what someone has to say.
“Own” your language. Instead of saying “You really screwed this up.” Try, “I see some ways to improve this.”
Immediately work to find common ground. What can you agree about? Once you articulate that, you will better be able to address the areas of contention.
Define how you’d both be better served by reaching agreement.
Keep the conversation on track. Don’t allow the other person to throw in the kitchen sink from left field. Simply say, “We’re getting into another area. Let’s get back to the original question.”
Deal with facts and observations, not inferences and judgments. Arguing about facts is difficult, however.
Don’t worry about “why” they behave the way they do. It really isn’t important. Instead, focus on how you can work with this person.