This is the third agreement from Don Miguel Ruiz's book The Four Agreements: "Don't make assumptions."
Don Miguel Ruiz says, "We have the tendancy to make assumptions about everything. The problem with making assumptions is that we believe they are the truth. Making assumptions in our relationships is really asking for problems. Often we make the assumption that our partners know what we think and that we don't have to say what we want. We assume they are going to do what we want, because they know us so well. If they don't do what we assume they should do, we feel hurt and say 'You should have known.' Making assumptions in relationships leads to a lot of fights, a lot of difficulties, a lot of misunderstandings with people we love."
The first step for me to make this change is to be aware: Aware of my actions, what I say, and how I show up in the world. When I am in assumption mode, I try to switch into clarification mode. Sometimes I might ask too many questions, however it helps me to get the information and clairify something I don't understand. It sure makes communication clearer for me. Also, to ask myself what I want and how to be in my authenticity. As I said before, it takes practice.