1. Images should be large
Large images are powerful. A full-slide image can easily create some sort of emotion. The key to using images is to keep them for emphasising a point.
You should be cautious about using images that are merely for decoration. But there is no doubt that images can be deployed in order to make a presentation more persuasive.
2. Images don't have to be in the middle
You can place some images at the edges of a slide. This looks good. The article on the presentationmagazine.com website mentions an attorney who was defending a doctor and wanted to show that the doctor used modern equipment.
So he placed photos of the surgery at the edges of the slides, thus reinforcing the message he wanted to convey.
3. Include enough blank space
The slides must contain enough unused space. Of course, the space doesn’t have to be white; it depends on the colour of your background.
You know what is meant here. Your slides should not contain too much clutter. Take a minimalist approach. The more there is on your slides, the less attention is left for you.
4. Use clear icons and short text
Nowadays icons are popular. But they must be clear and simple (they should consist of as few lines as possible).
If there are long texts to be read, your voice may even prove annoying or distracting to the audience. You want them to be listening to you, not reading your slides.
Also don’t use bullet points: the modern trend is to find a way to do without them.
-jk-