One of the most important things to do when you are trying to work with your co-parent is to remain flexible. Trying to stand firm on everything is just going to lead to frustrations. You are going to have to determine what aspects of the child custody situation are truly important.
As you are trying to determine what you are going to focus on, remember that the child's health and safety are the primary considerations. Letting the smaller things go can help to reduce your stress and help keep things calm with you and your ex.
When you are trying to negotiate parenting plan matters with your ex, take the time to listen to what they are saying. Sometimes, they might know something you don't or have thought of a factor related to the matter that you didn't think of. Actively listening can help you see where your ex is coming from with some of their wishes.
Try not to let your emotions rule you when you are negotiating with your ex. Trying to keep things logical can go a long way in the process since it enables you to put the children first. Keeping your emotions in check also helps you avoid getting too upset while you are trying to figure things out.