Read this book and a lot of messages will surprise you. For example, you will learn how self-centered we are when we think we should be expecting something from somebody else and how this blocks getting what we want. You will learn how to get away from that.
And be sure to pick the book up again before you face a difficult conversation.
This book has been a very great help for me in getting issues resolved without bad feelings for any party. Even just skimming over my notes and highlights before a difficult conversation removes tensions I am bound to have and puts me into a more constructive mindset.
This book is based on the famous Harvard Method for negotiating but more focussed on everyday conversations. Great insights and easy to read. Also contains many excercises to check and develop one's own ability to Deal with difficult situations.