It isn't easy! Here are some of my thoughts after raising four kids.
1. Parents should never raise their voices to teenagers. Much easier said than done! Still, once voices are raised, communication is over. Parents need to be the adults in the room, and model how they want teenagers to be. "Walk the walk." By not raising their voices, parents demonstrate respect for others. Even if teenagers raise their voices, parents should not raise voices in return. Parents need to be the adults in the room.
2. When parents do raise their voices to teenagers, the parents should apologize. "I'm sorry that I raised my voice."
When parents apologize they set a terrific example. Parents then model self-control, humility, the ability to admit a mistake, consideration for others, strength of character. Just what parents want to see from their teenagers! Parents thereby create the possibility that communication can continue or resume.
When parents apologize, they shouldn't also overreact to their mistake by automatically giving teenagers what they are demanding. "I'm sorry that I raised my voice. Sure, you can have 30 people over for an all-night drinking party." No, parents still stick to their position (when it is reasonable!). Parents thereby model that it is possible to treat others with respect AND, at the same time, discuss and negotiate.