Let's put in some of the basic lines. It's important to mark the light dot(s) in the pupil/iris. You can also outline some if the black parts that stands out in the reference. I usually use a mechanical pencil for this job.
Draw rest of the eyelashes and blend more shadow in. Now we can decide how realistic we want the drawing to be. Add as many details as you want, do all of them if you have the patience. I have added some of them.
Draw the rest of the eyebrow, and add shadow around the eye. Make sure to get the tone/shadow almost right, and then blend it. You can also add some tiny skin details; this will make it look realistic.