While in ILM Singapore, I gave a few portrait classes to the modellers team in Plasticine and in Zbrush.
For that class I made a few quick portrait practises as samples on how to go about sculpting portraits or likenesses.
All these portraits took me from 1 to 2 hours. I started from a sphere the first one and then transform it into the next one over and over.

Soon I will be uploading some video tutorials about portrait sculpting. Let me know guys if you would be interested and what would you like to see or hear.