Science of picking colors that work well together in Adobe Illustrator

Just to add to Colm Tuite’s answer, using contrast is critical when forming a striking image.

Complementary colors reflect the color that is on the opposite side of the color spectrum when viewed as a circle. Here are some additional standard colors. It is not by accident that you will commonly see some of these opposing shades in the same design.

I gave the image only as an example of contrast and complementary colors. It was by no means complete nor exclusive. Also, then worked with and on the concepts involving color up to his death which like it or not influenced many artists today.

Take for example this he made in 1961: not the thirties.

Also, there is very real science to opposing colors. Stare at a red
screen for two minutes and look over to a white screen, and you will see
green because the red cones in the eyes become over saturated and only
The green and blue cones can properly see the “white” light. Thus
everything is hue shifted green.

These colors are biologically the opposite colors, and one contradicts the other in our eyes.

For an example click play to start the gif animation, then stare at the tiny black dot in the middle of the image below and keep staring until the timer reaches 0. The effect I describe will cause your eyes to see color in a
gray scale image…

Read: How to change Illustrator Background Color

To prove this is not a trick watch it out of the corner of your eye then look directly at it when the timer reaches 0.

It’s black and white, but the orange saturated the color receptors other than blue, so you see blue in the sky etc…

By the same token if your color receptors are being saturated by one
color and there is another complementary color present it will stand out