Understandably, parents who are going through divorce often have a difficult time meeting each other on common ground in terms of child custody arrangements. If this is your situation, then it may be a good idea to make a list of things, no matter how small, that you both can agree on, and then try to build from there.
For example, maybe you and your co-parent can agree that staying with the same pediatrician is the right decision. If you both agree about your child's extracurricular activities, then maybe that can be added to the list. Really, any number of points of agreement may serve as a foundation for a long-term solution.