Difficulty with Zbrush Facial Sculpt

Hi guys,

I'm unsure whether this is the correct place - but I hope so!

I'm having difficulty sculpting a characters face for a personal project to improve my anatomy skills. I've looked through the wiki and 3dsk for some good reference material, and just wondering if there's any workshops or diagrams etc of facial proportions that will help me understand how to sculpt here more effectively.

Cheers David