This time I will not use a hand draw sketch, but an image of a real skull. I got mine from a museum that I've visited a while back. Note: If you try using pictures from museums or expositions please check the copyright issues with the museum's personnel before using pictures of exposed items. If you don't plan to visit a museum soon, you can access the source image of this tutorial, and use mine.
Open a new file in Illustrator (Command + N), browse on your computer to where you have the picture of the skull, select and copy it (Command + C). Go to Illustrator again and paste it (Command + V) into your Illustrator file.
Now that you have the skull image in Illustrator, you need to lower the transparency so you can trace it easier. Select the picture using the Selection Tool (V) and bring down the Opacity to 70% from the Transparency Box (Command + Shift + F10).
