I've done an eye tip sheet already but there's still a few more things i need to cover.
Making to eyes look like they match or are inline on the face is one of the most difficult things to draw besides hands. The only way to do this is to practice and become consistent but i have a few tips to that will hopefully help.
I always draw both eyes at the same time. ( as seen in the above pictures) this helps with consistency and gets the sizes similar. They eye further away is has less width and looks more compressed than the closer eye. Also remember at that angle you can sometimes see the curve of the eye and/or the eyelashes.
Best way to tell if you eyes are in proportion is to flip the image, you will be able to tell right away what is out of place if you do this. If your drawing on paper, turn the page around and hold it up to a light, this creates the same effect as flipping the image. This can also be used to tell what else in the picture is/or inst in proportion.