Transitioning to a co-parenting model for child custody isn't easy. This model relies heavily on you and your ex being able to work together. This doesn't mean that you will always agree, so you should have some guidelines for how you will handle conflicts. Guidelines can definitely take some of the stress out of disagreements -- but so can remembering that every disagreement doesn't have to result in a battle in the first place.
In other words, you can learn to choose your battles over the kids with your ex.
How do you determine what to argue about and what to let go? One thing that might help is asking yourself if the kids are happy, healthy and safe. If the answer to all three of these is affirmative, you may be able to let the situation go. If the answer is negative, the issue might be one to dig your heels in over.
Disagreements also often stem from miscommunication. You can avoid unnecessary problems if you set clear communication guidelines in your parenting plan. Make sure that you keep an open mind as you negotiate.
When issues do arise, ask your ex about the situation in a nonconfrontational manner. Think about what you are being told. There are some cases in which a willingness to try to understand the situation from your ex's perspective can help diffuse tensions.
No matter what kind of conflict you have with your ex, remember that remaining calm can help to control how tense the situation gets. Neither you nor your ex should ever be afraid to take a bit of time away from the situation to reconsider your options for handling the matter.
Remember, the goal is to have well-adjusted children who can thrive in their environment. The best way to achieve that is to find a parenting plan that works -- no matter what your relationship with your children's other parent is like.