To make sure that a message gets across, it's important to tell people what you want them to understand more than once. While it may feel redundant, I try to: tell people what I'm going to say, say it, and then tell people what I told them. For added effect, I'll alternate between media. In a work setting, I tell people that I'm going to email my findings in person. Then, I email my findings. And lastly, I confirm that my findings have been received properly over chat.
In each interaction, I share the key takeaways, so people will be more likely to remember my conclusions, even if they forget the specifics. But, I'm careful to make sure that people don't feel like they can just wait for me to remind them of what I'm trying to say again later.