The brain loves patterns! Drawing simple patterns actually helps you become a better visual thinker and pattern finder, even when things are more abstract. And it helps you to more quickly find the simple patterns in more complex ones.
Duplicate a black and white pattern design four times. Choose four colors, plus tints or shades if needed. Color the background the same on all four images. Then use the other three colors to color the main parts of the design, making each of the four copies different. Then put them all together and see how your original simple pattern suddenly becomes much more complex.
I did this one in Photoshop and flipped some of them horizontally to make things even more complicated, yet the original design is still quite simple.
See this previous blog post to see how to make this pattern and this for an exercise with color.