All propaganda argues for or against something. It’s trying to make a point.
Your goal is to make people change what they think and even how they act. You need to determine what actions you want to achieve, what feelings you want to evoke.
Propaganda is designed to target a particular audience. You must know what that audience has and values, desires to have, and fears.
Propaganda tells a story. By simplifying motives, it creates a hero and a villain. The hero defends everything the audience cares about while the villain threatens it. This requires name-calling and simplification of motive. The villain will be old or ugly or deformed the hero young and healthy.
The propaganda predicts consequences of accepting or rejecting hero’s cause. Consequences will be simplified "Elect me and I will fix the economy." "Don’t wear a seat belt and this mangled body will be you."