Nobody really asked for this, but...
Here's an eye tutorial!! Hope y'all find it useful

Instructions:
1. Sketch the eye, you can begin with the eye shape and then the iris, then you can draw the eyelashes afterwards. It can be as simple as you want, or you could make your sketch more detailed.
2. Add a layer underneath the sketch layer then add the base colors. Add some shadows and lighting, don't just put them randomly, think about where the shadows and light should be so it won't look awkward.
3. Add a layer on top of the sketch layer and paint over your lines and blend them together (You should use a soft brush, you can also use airbrush but don't overuse it). If you want to make your colors look more interesting, try to add the skin tone color to the eye.
4. Make it more detailed as you go, draw the eyelashes and add some soft lightings to the eye.
5. And the best part... Highlights!! Add white highlights to make it look glossy.

(Note: You can always use a reference as a guide)