Here are some different eyes that are mainly used for comics or manga. Mainly the eyes reflect what's inside the mind and heart- that's why eyes are very expressive. Keep in mind that in comics and manga, the eyes play a very important role. You may notice light circles underneath some eyes. Mainly if you want to build a good eye, you have to start with a circle (like in many other things!). Obviously after years of practice and experience, one will make them on the first attempt without making any consturction circles.
Anyways; practicing eyes is very important... Men eyes are different from female eyes. Females have more lashes and may be more pointed on the outside part. Male eyes are more narrow and rectangled shaped. Here is a mix of both: