Some of the strategies used in propaganda include:
-presenting only some information
-presenting information only subjectively, from one point of view.
-presenting opinions of only one side of the story, including in a very convincing and emotional way.
I think that the last one is the one with the biggest impact (-presenting opinions of only one side of the story, including in a very convincing and emotional way). This is because we humans often identify deeply with other humans, so if we listen to someone's side of the story and don't have access to the other side, we are likely to trust this side.