Stick to the salient points. Use different slides for unrelated ideas. Three to seven lines of text per slide are enough. In general, a single illustration should contain a single graphic, and complex graphics should be avoided. For legibility, titles can be centered, but following lines of text are easier to read if left-justified.
Bullets can provide an additional left anchor to organize related text.
Simple typefaces are easier to read. Times is good for columns of printed text where the eye does lots of scanning word by word. Where fewer letters are present, Helvetica is a clear, well-proportioned typeface. Using BOLD can help emphasize a word or phrase, but italics and underlined text may be hard to read when projected. Although using two typefaces may help to distinguish particular kinds of information, be sure to use them with a specific purpose.