Looking to get a good idea of how some effects and attributes of source were accompished? Want to make your work look fantastic? Take a gander at these articles (PDF) on texture painting, surface properties (specular, reflective, bump map, etc), and some very good photoshop tips/tricks for custom materials for in game, or models. All the info covered is interchangable information for modeling/mapping.
I suggest reading this first tutorial before the second if your completely new to texture creation:
http://www.onona3d.com/pdf/texturing.pdf
http://www.onona3d.com/pdf/PhotoshopTips.pdf
The second one covers correct use of the stamp tool, and accurately making seamless repeating materials
And if you need a good guide for modeling a face (Good face modeling tutorials are rare) Here is a great one using the polygon extrusion technique:
http://www.3dcm.com/facemodeling/tutorialfacemodelingIndex.html
Hope you find them helpful
And dont be lazy, read all pages GOD Damnit!