How your characters react in your story are the heart of your story. For example, If you want your character "Bob" to get a strong reaction from the audience, make sure other characters in your story have a strong reaction to "Bob".
Imagine someone is questioning you over every slide in your presentation. "Why did you put this slide in? Why do you need to have this slide?" How would you answer them? If you can not defend the purpose of a slide in your presentation, leave it out.
Pull your audience into your story with phrases like, "If you had been there, you would have seen me...", or "if you have ever been in a traffic jam, you know how I felt...". This keeps the audience focused on your story while at the same time they connect to their experiences.
To get the audience involved in your presentation give them an "assignment". Give the audience a task to complete or something to listen for in your presentation and they will be forced to pay attention to what you are saying and doing.
"Youify" your speeches and make sure we say "you" to your audience often. This makes sure your speech stays focused on your audience and their interests.
When you get to a speaking event, there is not enough time to focus on practicing the entire speech again. So only focus on delivering a great opening story: if the opening story goes well, it will get everyone interested in your speech.
Before giving your speech, take the time to visualize it in your mind, seeing it go well and making a strong impact on your audience. If you can see the speech going well in your mind, you can work to bring this "mental view" into "physical reality".
If there are more chairs than people at a speaking event, put away (or move out of the way) the extra chairs so that the audience sits together (and doesn't spread out in little pockets all over the room). This will keep your audience's energy focused and powerful.