My children are young so it mostly only applies to my oldest two at this point
We all have to treat each other with respect and their things and space
We all have to eat dinner together every night at the dinner table
They must have their rooms picked up before dinner everyday, so it is ready to go for the next one.
Bedtime is 8 pm no ifs, ands, or buts about it!
No back talking to mom and dad
I start with a time out. If they choose not to follow these rules. If they are fighting over toys or not sharing the toy is taken away until they can play nicely with each other. Depending on the back talk a small spanking is sometimes used, but I try to get them to correct the behavior, by having them say an appropriate thing first, which normally works.