Ground rule: Develop tiebreaker tactics for when you get seriously deadlocked.
One good strategy: Find ways to make each parent a primary decision maker, part of the time. "My husband is a total soft touch," says Janis Mysona of San Francisco, mom of Hannah, 13, and Abby, 10. "He works long hours, and when he comes home, all the rules tend to go right out the window. It would be way past Abby's bedtime and I'd find David and her cuddled up in the family room, watching TV. I'd have to break up the lovefest and order her off to bed. David would jump in with 'But I've barely seen her all week, and we're having such a good time.'"
After months of battles, during which Janis felt like the household killjoy, they came up with a plan to bring the situation under control. They decided that, by and large, Janis would call the shots on weekdays, and David would rule the roost on the weekends. "He's got a long wick, and that's fine on the weekends. I'm the disciplinarian, and that's what's needed on weeknights. Now that we've agreed who's calling the shots when, we pretty much know where things are heading and don't get into big blowouts over 'Yes, she can stay up another twenty minutes,' or 'No, she can't.'"
Other ways to deal with stalemates: Agree to let the parent who feels most passionately about the issue at hand have the last word. Or defer to the parent who swooped in on the touchy situation first. But make sure each of you has some victories under your respective belts. If one parent always wins or dominates, the system isn't serving you well.