What are you promising?
Every job that requires communication is always about selling something. Maybe not for money. But there's always some sort of exchange. It could be you trying to get students to learn something, getting your boss or employees to adopt an idea or convincing shareholders in a presentation.
It all starts with an idea which is what you want to communicate. You then rephrase the idea in the form of a promise that will help them solve their problem in some way. The next step is the pitch which is what gives them an incentive to have their problem solved. Lastly, you call them to action with an offer or a choice they have to make.
For example, if my idea is getting students to learn then maybe I lead with the promise that learning economics will help them understand the world a little better no matter what they do in the future. My pitch would be that an introduction to economics doesn't require much skill in English or mathematics. Finally, I call them to action by telling students all they have to do is do the assignments I've prepared for them.