Hello dear anon, The best way to draw eyes is to use guide lines. In 1 the guide line on the left (blue and red) is the one I normally use for my own drawings. The lines plus the space between the 2 horizontal lines are the main guide for the eyes, however the size will alter depends on the character and angle of the face.

There is lots of tutorial online, as well as PDF books available that discuss the guide lines in depth. I would highly recommend Andrew Loomis’ books. Drawing the head and hands, Figure drawing for all it’s worth. (You should be able to find the PDF version of it online easy, however if you have any trouble locating the book let me know.)

Hope it helps!