How to draw eyes shape - more-or-less formal algorithm
Welcome to the A&amp;C, Code Complete. 

The thing about eyes, is that all of them are not the same shape. Sometimes the eyeball can be referred to as, 'football shaped', 'almond shaped', and many different other types. Here area  few different ideas below (You can even Google "Different eye shapes":     



Like the image you provided above, there isn't that many 'dark lines.' in the eyeball, eyelid itself. Most of the 'dark areas' are only in the eyelashes, and pupil. If you look at the bottom eyelid there is no dark lines at all. The only dark parts you see in the bottom eyelid is the eyelashes. The corner right part of the eye is darker(where it attached to the upper lid. But is not black either. It is more of a medium brown.

Having to learn about blending and shading, tortillon AKA blending stumps can help. Also looking into drawing pencils that do not write as hard.    

(tortillon image below)



(Different hardness of drawing pencils below)


Those tools will get you in the right spot to begin to draw the human eye.