Many people put only one color on. But do u want the model look? If u don't want the model look, then u can just leave and find something for PLAIN.

Model look #1: Put a light color on. Up to the first of seconde eye line. Then take a dark color. Try and make it a darker version of the light color.
EXAMPLE: Lome Green+forest green

Model look #2: take a neon color (preferably orange) put it on the corner and when u go past the corner, kinda swerve on the top.
Them take a pretty color such as blue of purple, and put it a bit smaller than the oranje one. (Still swerve up) And now choose your last color… and do the same

Try out some other things! Be creative