Don't use color only to convey information.

Charts and Pro/Con lists are a typical place where we see people use color alone to convey information. When these items are rendered in black and white, that information is lost. Just the same, when individuals who cannot see color, such as those who are colorblind, come across these pages they cannot understand the information. 

The following are examples of line charts that use color to convey information. Although color can be used, using line styles as well is the best practice to ensure an accessible looking graphic. 

Example: Chart that uses color only to convey information

Example: Same chart that uses color only to convey information, in black and white

Example: Chart that uses line style to convey information