Talk about what you show, show what you talk about

Too often the speaker creates a narrative that differs from that portrayed on the slide. The speaker's role is to explain the slide. The speaker needs to create a synergy between the oral and visual presentation.

If you portray something on a slide and don't discuss it, you need to ask yourself, "Why it is on the slide?" Remember every unnecessary detail on a slide makes it more difficult for the audience. If you don't discuss it, it probably shouldn't be on the slide. Conversely, if you are going to discuss a point, it should normally be reinforced by a visual on the slide.

Build a presentation up, don't cut it down!

One of the most common mistakes is to start with a mountain of data and ask, "What can I cut?" Everything seems indispensable. As a result, scientists typically include far too many slides and rush presentations.

A more effective strategy is to identify the core message and "build up" from that message; adding detail in a manner consistent with audience knowledge and available speaking time. Add only detail that supports the core message. Start with a one minute version for a relatively unspecialized audience and ask, "What would I include if I had five minutes?" Repeat the process until you can fill the time that you have available.

The above slide shows this as building the presentation "up" from a single slide rather than "cutting" down from many slides.

More guidance on how to develop that core message in future tips.

Write a summary slide for each section of your talk, even if you don't use it.

You should probably use an outline slide in your presentation and return to the outline after each section of your talk.

I recommend creating a summary slide at the end of each section and before you return to the outline slide. This slide should recap the points the audience should have learned from the slides in that section.

You may ultimately choose not to use the section summary slides in your oral presentation. They may make the presentation too repetitive and pedantic. Still the process of making the summary slide will force you to consider whether the audience has learned what you want them to learn. Perhaps more importantly, it will force you to think though what you want the audience to learn!