Look and look. It's not always criminal to trace, especially if it helps you become familiar with (whatever you're painting).
And eyes are really expressive and say so much that it's hard to say what to do, because subtle inflections and changes will change the whole thing you're trying to project.
And a lot matters what you're style looks like, what animal or human's eyes you're doing, the lighting, etc.
So in other words, find excellent source material and copy until you get to where you build an understanding.
The internet has lots of stuff.
Good luck. And it'll be fun for you to see your own visual power as you get a handle on it.
"Not a bit is wasted and the best is yet to come. . ." -- remembered from a dream