Too often we forget that good foils should have at the most eight words. Another rule states that a foil should contain no more information than can be understood in 15 seconds. Many of our foils are still overcrowded. Sometimes I wonder why opera glasses, those little elegant binoculars used in the theatre, have not become more popular for presentations. And choose clear, simple wording.
Catchwords are sufficient, as one can still explain verbally what is meant.
Complete sentences should be avoided on foils, as listeners cannot really concentrate on what you are saying while they are reading them. Sheets, whether on an overhead projector or on Powerpoint, should never distract listeners from the attention your speech deserves. Supporting media should do just that and neither crowd out or replace you. The effect of a pause is often greater than if you chatter on while your listeners are trying to read a joke on your foil. Make use of all available media for your presentations.