Love your kids with everything you've got. Let go of your ex, as best you can, and focus on the impact your love is having on your kids. Stay true to that value and you will always choose the high road.
While I don't blame my then-wife for "going for it" and asking for everything she wanted: the money, the house, the custody, I don't think she was thinking beyond her interests. And we can all cite studies about mothering and nurturing, but today, just as many modern studies show the dad is of equal importance in bringing up healthy kids.
It's all about the kids. If you've still got a beef with your ex you need to get over it. There's no point. You might have disagreements about stuff, but those should be handled with the same intensity as a convenience store clerk.
I felt like I had a pretty good idea of the way the divorce was going to go, once I agreed to actually get a divorce. We went, eyes wide open, into the negotiations about parenting rights, money, schedules, and I also felt like I had a cooperative soon-to-be wife who was not going to try to destroy me. The first part was true, the second part, well...