"The first step is to accept a child's right to say what he or she has to say, no matter how stupid or unreasonable. You don't have to listen to all of it, you can leave whenever you want, but you respect their right to say it. Then you say what you have to say, you stand your ground and are not blown away from by the inevitable response. This kind of parenting earns respect. It's the strength not to descend to teenagers' level of name-calling, when they would lose respect for you. It's the strength to walk away."
Details can be found on Ravelry.