DO

• Always label your axes and include the units for the y-axis.
• On the y-axis, choose increments that are easy to follow. All values on the y-axis must be divisible by the increment itself.
• Display negative values below the zero baseline.
• Start the y-axis at zero when you have values close to zero.

DON'T

• Don't use more than 10 data series when using multiple lines. More is not always better. Plot the data that helps you get your point across.
• Don't use a double scale on the y-axis when comparing same data series.