Symbols - Symbolic diagrams and flow charts are useful if not too detailed. Use standard symbols if possible. Structure and Relationship - Simple schematic diagrams effectifely convey the structure of systems or relationships of objects. Show only what is necesssary to explain how a thing works. Tables - Don't use detailed tables.
Tabular data are more legible and more easily compared on graphs or charts.
If you MUST make a table, keep it simple and include only items that you will mention. When you Digress from the topic of the slide, use a blank slide , colored and shaded, not white, to darken the screen. Never say one thing orally and something else visually on the screen . It confuses the audience.