Let’s start with some more colors and fonts…
DO analyze the color undertones.
If you like blue but want a subtle effect, choose a white or grey with a blue undertone. A red-orange terracotta pot has a yellow tone to it; hence those colors will blend harmoniously with each other. On the other hand, don’t emphasize an undesired undertone by pairing it with its complement: if the shade of brown has a pink undertone to it, combining it with green (the complement of red) will only intensify the problem.
Learn to identify color tone, its warmth or coolness. A warm blue contains some red that makes it to look purple, while a cool blue contains some green, which makes it more aqua or teal.
Do keep in mind that neutrals also have undertones. Often people will mistake grey for blue if there’s a blue undertone, or plum if the undertone is violet.
DON’T neglect the fact that colors ‘change’ according to their surrounding:
A large rectangle and a narrow line (or type) of the same color will seem to have different values when placed against a white background: the color in the line will look darker than it does in the rectangle, because it’s surrounded by much brighter white space.
When two shades of the same color, one dark and one light, are paired with each other, the darker shade will look darker and the lighter shade will appear to be lighter: a pink rose will seem to be paler against a purple background.
Larger color spaces will affect the smaller ones: if a small square of medium yellow is surrounded by a larger area of black, the yellow square will seem to be brighter than when surrounded by white. Any color will appear lighter against a darker color and vice versa.
Outlining a color in a darker shade will enhance the enclosed color, helping to keep a color from “spreading” into surrounding areas. On the other hand, a lighter outline will cause a color to spread to adjacent colors, and reduce the strength of the enclosed color.