MR. SUPER CLEAR IS A GAME CHANGER
Step One: Prime your Eye mesh. I use Mr. Super Clear. Use outside with a respirator and coat the eye mesh before you start painting. I use this stuff to make the paint stick to my eye mesh better. It makes for an all around better project.
Step Two: Paint. Layers while painting is crucial. Start with your gradient, then let it dry before adding more.
Step Three: Seal Your Eye mesh. Afterwards I use a Matte clear coat to seal the eyes and make them waterproof.
I use different meshs to paint. This one is a banner material that is printed white on one side and black on the other.