[kabdib]

Two tips:

Use colors in /addition/ to other indications. Roughly ten percent of males are red-green colorblind and cannot easily distinguish colors that contain these colors (e.g., purple = blue + red = BLUE to them). Also, projectors are usually pretty crappy at colors.

"If PowerPoint ever automatically chooses a smaller font for your text, you have too much on the slide." -- somebody wise

[kikito]

Yes, this is something I should have written explicitly. Your advice is spot on, I should have included a "conclusion" in the colors section saying just that.