There is an excellent essay on that, by Dr. Elgin, at Ozarque.
For a taste of what she is saying:
The essay has a number of good rules and suggestions and some interesting comments.
Rule 1 (The It-Should-Go-Without-Saying Rule)
Don't swear, don't use obscenities, don't use name-calling, don't use open insults, don't yell, don't get physical. Be civil.
Follow the language interaction traffic rules. That is: Listen with your full attention when the other person is talking; don't interrupt the other person; don't monopolize the conversation by delivering monologues instead of taking turns; don't have a tantrum.
If the other person does monologues at you, follow these steps.
Step 1. Match the rhythm of your body language to the other person's. Blink your eyes at the same rate; breathe at the same rate; nod your head at the same rate.
Step 2: Once your and the other person are synchronized for body language, start synchronizing with the words being spoken, saying something innocuous, speaking -- softly -- along with the other person and at the same speed. Use a phrase like "I hear you" or "Mmhmm" or "I see." Choose one phrase, and stick with it. You're not interrupting when you do this; you're supporting and helping. It's like pulling ahead of a car whose driver is obviously lost, getting the driver's attention, and leading the way to the next exit.
Step 3: Now that you and the monologuer are nicely matched, start slowing down your words and saying them more and more softly. Do this very gradually; let the other person follow you, very gradually, toward silence.
Do your best to put out of your mind the Disagreement Is Combat metaphor, where you blow the other person out of the water, tear their case apart, shoot down their arguments, and are obligated to WIN, no matter what it takes. Try Disagreement Is Carpentry instead, or some other non-competitive metaphor of your choice.
In addition, her book on the topic is still in print and available at Amazon.com or, in a special edition, at Barnes and Noble.
If you find yourself fighting or in the grips of continual disagreement following the death of a child, it helps to learn, once again, how to disagree without turning it into a cause for fighting.
Available by interlibrary loan almost anywhere.
BTW, as to one of her points, another sort of three part message
If you feel that you cannot avoid making a critical statement or a complaint or a request for a change in behavior, use a Three-Part Message for that purpose. [Posts on Three-Part Messages are at http://ozarque.livejournal.com/109401.h
tml, http://ozarque.livejournal.com/110486.h tml, http://ozarque.livejournal.com/109957.h tml, and http://ozarque.livejournal.com/110211.h tml.]
I'll be blogging on that three step method and on how to tell people you love them (another three step method) in the future.