In February 2014, my first video course was published over on Tuts+, Vector Portraits for Beginners. It's completely free to view (sign up required) and it takes you through some fundamental skills in creating your own vector portraits in Adobe Illustrator.
It covers two main projects aimed at beginners: creating a line art based portrait and creating a shaded portrait. If you're familiar with Illustrator, then this course will be perfect for you.