All presentations should tell a narrative that includes a beginning, middle, and end. The first part of your presentation should always present the problem--ask yourself, "What are we going to solve today?" The middle of the presentation should present your key findings, but they should always tie back into the central issue you want to solve. By the end of the presentation, your audience should feel like they've learned something, and that they have a better understanding of the solution.
Often, people have a tendency to overcomplicate a presentation slide with flashy images, quirky transitions, and too much text. These features are often unnecessary, and tend to make the viewer tune out. "It becomes like wallpaper," says Jim Confalone, the founder and creative director of ProPoint Graphics, a graphic design studio based in New York City. "Their eyes will glaze over." Instead, keep each slide free of clutter, using one image to sell your idea. Using bullets is a bit of a cliché, but if you must use them, never exceed one line of text per bullet.
According to a recent research paper from the University of Tennessee, the average adult attention span for a presentation is just 20 minutes. It's always best to keep your presentations short and to the point, but if you must exceed the recommended 20 minutes, try giving your audience a moment to relax. "You can prolong attention spans by periodically giving your audience a rest," the study says. "This can be done by telling a story, giving a demo, or doing something else that gives the brain a break." Steve Jobs offers a perfect example: during one presentation, Jobs pulled up a blank slide--not as a mistake, but as a way to help people relax and maintain their focus.
In the end, a great presentation will come down to the speaker's ability to capture the audience's imagination--and keep their attention. The presentation and the speaker should work together, meaning the slides should complement the speaker and the speaker should complement the slides. The best presenters won't have to look down at notes, and they'll never be reading from a script. Focus on the key points, and let handouts or packets outline the minutia. A good speaker can convey information well; a great speaker will sell an idea.