That's quite easy if you know something about make-up. If you have no experience, please follow my suggestion.
First of all, go straight to the department store then buy some make-up stuff, such as eyeliner, eye shadow, and mascara,etc. Then you can search some make-up teaching videos, then follow them to draw own eyes. That will be immediately helpful. But as a beginner you may not be smooth to draw the perfect eyes.
If you do not fancy make-up, or feel it's hard, I mean for me, it’s really a hard thing because I'm so lazy. Then you can choose to be cosmetic contact lenses.
Cosmetic contact lenses can make your eyes be rounder inside, and make-up will make your eyes be bigger.
If you want both of them, just do that all.