Knowledge is power

The more comfortable you are about your topic that you are presenting, the more easier it will be to present it. When you are doing a presentation you should always know 100% about your topic, that way, even if you forget to include something in your actual presentation, you can mention it off the top of your head.

Knowing a lot of facts will also lead you to a more applicable presentation and a confidence that allows people to trust what you are talking about.