Make unimportant things grey

Grey is a very useful color for things that aren't very important!

Use grey to color elements...

• that are unselected or backgrounded
• elements that provide context to an important data point
• that are not the currently selected element

In fact, let's just make grey the default color. everything should be grey unless you'd feel comfortable shouting that data point out at a stranger.

If you're using hex, #e1e1e1 and #f3f3f3 are two nice light greys that I'm personally fond of.

Example

You have a line graph of life expectancy over time for 20 different countries. You're currently interested in India.

Make the 19 countries that aren't India grey, and then India gets to be red or green or whatever your favorite highlight color is.

Picking colors

You can pick your own colors if you're a design genius, but if you aren't just use http://colorbrewer2.org and you'll probably be okay.