Be respectful. Be respectful of yourself and others. Recognize that you may not be the only one hurting in a situation or that someone else may have a different experience than you which is not necessarily invalid. Also recognize that you have needs and be willing to address them and make attempts to take care of them. When you respect yourself and others you leave room for acceptance of mistakes because of the trust that is built.
In the heat of a moment it can be hard to remember all of these tips for better communication. If it helps you go ahead and take a copy of this with you or make flash cards with the ideas that feel most important to you. You can them take the list out when you are feeling like communicating isn’t going so well or you are about to try to communicate something and use it like training wheels until you are more familiar and comfortable with the steps. Given time and effort you will gain more and more control of your end of communicating and this will lead to feeling more in control of your relationships.