Hair is fun but it can be a challenge. It is fun because your pencil marks are nearly identical to hair and you get quick results, and a reward, for each mark you make.
I have posted here an outline and a few hairs on the left side of the drawing. I have darkened it because I used a 2h lead in a .o7 mechanical pencil and you barely could see it in the first scan I did.
You can also notice I do the left side first because I am right handed. I won't come as near accidentally smudging the rest of the drawing when I start on the left side and go to the right. I'm sure most people know they can also put another piece of paper under their hand as they draw. Just don't let the paper move. Let your hand move on the second piece of paper.
As you can see in the cropped enlagement I leave the white spaces last and draw in the darker hair and shadows first. Then I come back and do more detailed drawing of the negative space around the white hairs.