It can seem like a daunting thought, how to successfully paint eyes.
Well, I'm here to tell you it is only in the detail and that DOES NOT HAVE TO BE DIFFICULT.
KEEP IT SIMPLE
Here's an example from a little sketch I did of Hamish the cocker spaniel.
The viewer is drawn to the eyes, as we are with faces generally. In this example it looks complicated, but here's a close-up to show you it is purely small hints of colour and leaving some white paper.
Sometimes the things that seem to be the most difficult
are the easiest.