When creating documents, make sure that graphs and uses of color are legible when viewed without color. Roughly 1 in 20 people are color-blind. And, regardless of a person’s ability to see color, it’s common to print papers in black and white. If your paper requires color to be understood, then you will lose readers!
For slides, color can play a more important role. You should make presentations accessible to color-blind people, but complete color-blindness is very rare. Most color-blind people are either unable to distinguish between red and green or between blue and yellow, but otherwise distinguish between other colors. Thus, if you pick your colors carefully, they can be seen by almost everybody.