A very useful tutorial : Hair drawing tutorial - We highly recommend this great tutorial by Tomáš (Timon). Drawing hair is definitely one of the trickiest part of almost every portrait. In this tutorial, Tomáš introduces some easy and effective ways to draw wavy or straight hair or hair blowing in the wind. A huge thank you to Tomáš for this very interesting lesson.
This drawing tutorial explains everything you need to know about drawing hair on your portraits, and uses celebrity hairstyles as examples.