That the viewers conscious and subconscious will get what you are trying to say.
A professor of mine used to say (and most likely still says), tongue In cheek of course, “if you’re not cheating, you’re not trying”. If you are wondering about colors in your design, pull out the trusty color wheel and cheat a little. I suggest that you first choose your primary color based on your thorough research on the client and the audience and all that jazz. Then, if you’re having trouble with a second or third color, cheat.
Look across the color wheel at the complimentary colors, look to the left and right for the analogous colors. Now choose some possible combinations.
Then once you’ve chosen some options, research the color psychology of reach color and combination to get the best scheme for your design.
Now this tip is not meant for you to just blindly spin the color wheel eyes closed and randomly choose colors. Use the color wheel to cheat the smart way. Because design matters.