It's sort of like a programming language. It won't turn a shitty programmer into a good one, but it will turn a good programmer into a more situationally effective one. The hardest part isn't learning the programming language, it's becoming a better programmer.
The first lesson in the book I learned from, Crucial Conversations (https://www.amazon.com/Crucial-Conversations-Talking-Stakes-...), is to recognize when you are becoming emotionally driven (angry, defensive, etc.) and to step back from it. Another key lesson is to focus on identifying and solving the collective problem - the key point is that in the vast majority of cases, especially in the workplace, there is a formulation of the problem such that everyone is trying to solve it, but they are just disagreeing on how to approach it. In my own experience that's been consistently true.
These are both introspective processes of first getting yourself into the right mindset and then employing the communication tools. Learning to first be generous to other people was the hardest and also the most crucial change, whether or not I had communication tools to go with it.