Things that will make people stop listening and move their attention elsewhere.
Raising your voice.
Imposing your own topic.
Using more than three items in a list.
Not making pauses.
Not letting the other speak.
No form of personalization.
It does not matter if your idea is the best in the world, if you do any of the above you stand no chance to make an impact. Thinking about how many organisations out there have at least five of these dealbreakers in their communication on a regular basis.