Expectations, lay it out whatever it is. That was anything from chores (not paid, they don't get a choice) that homework was done every day, before tech. Family time, what lifts they could expect. Attitude, tone of voice and manners. When we walk through the door with shopping, they should help unpack it. We would not accept being spoken to like dirt on their shoe and then do favours for them.
Family meetings where they get to negotiate what they want, later bedtimes, money, etc. It makes them feel heard. We called them table talks, anyone could call one, they also understood that we may need to discuss things as parents and come back to them, so a decision may not be immediate.
Don't shout even if they are yelling. There was an expectation that everyone tried to communicate with talking, calmly. I was raised in a shouty household. I hated it. That a conversation can have a break in the middle of it for everyone to calm the fuck down.
A reminder that we too were once teens, that we are not doing things to spoil their fun but that we worry about them and love them enough to piss them off. There was a tv show where someone was pulled out of a party by their parent, the teen complained that everyone else was staying behind and the parent publicly said well I care about you their parents clearly don't.
That no matter how badly they fuck up we would help them moving forward and draw a line under it. The same if their friend fucked up, we could offer advice via our child. Sometimes problems are so big they need an adult to step in, that includes bullying and notifying the school.
We also set them up for success, their school timetable printed and put up in several places around the house including the back of the front door. Helped establish a routine for emptying their school bag, doing homework, packing their bag. Let them problem solve rather than doing it for them. Walk them through scenarios like what would you do if the bus didn't turn up? Let them try to figure it out before you wade in.
We showed them Harry Enfield and Chums with Kevin turning 13 and his general shitty attitude, although funny not something we would accept. We did do it back to them when they asked for lifts/food, the whole moaning, huffing, swinging arms for fun, you have to do humour.
Good luck.