Don't try to be Complete
When people present some topic, many try to cover the topic very thoroughly. Don’t do that. Except your trying to kill your audience be letting them sleep until they starve to death. A presentation shouldn’t try to explain an idea completely. The aim of a presentation is to make the audience curious.
You can provide a couple of facts and maybe your audience will remember then. But the important part is to instill the hunger for more as well as providing the resources to learn more.
This is pretty obvious true for short calls to action. But I think this is even true for highly technical, rather lengthy talks. Even for workshops.
Imagine you are attending a one day workshop for a new programming language. There is no way you really understand that language in one day. But what you can expect is: To understand some basic ideas. To feel why it is worth learning this language. And a bunch of links, videos and books to learn more about it.
If you try to be complete you’ll end up with something that sounds like the public reading of a Language Specification. Nobody wants to hear that.