The first two is where most people stumble. Before I started to read communications books, I (as with many others) would focus on improving
my wording. How did they not understand? Let me be precise and concise so there is no room for confusion. That didn't improve things. Let me be verbose and say the same thing 3 times in different ways. Nope.
Coworkers would do something different from what I requested, and then claim I had asked them to do it. I would go to them in frustration, have them to pull up my email, and ask them to point to the line where I made the request they claimed I had made. I was that guy.
Finally, after reading the books, I understood that you can say things perfectly but should not expect the other party to understand! The only solution is to ask the other person to reflect back what you said. And to do likewise when they speak to you.
Communications is lossy. At the first level they may not have heard (e.g. noisy environment). At the next level they may not have processed it (e.g. zoned out because of some personal problems they are dealing with). At the next level, they may have processed everything, but interpreted the words very differently from what you meant. You cannot change any of these things. Don't (overly) focus on how you said it. Focus on getting them to reflect it back to you.