Slides that support you instead of replacing you

If the slide contains your script, the room reads it faster than you can say it and stops listening to you. One idea per slide, few words, and anything that has to be read in detail belongs in a handout given afterwards rather than on screen while you talk.

Charts follow the same rule: one point per chart, labelled, with the point stated in the title rather than left for the audience to derive. And build for the back row — text that is comfortable on a laptop is frequently unreadable from six metres away.