Panzer Striker,
Kalmbach has a pretty good book out called
How to Paint Realistic Military Figures, second edition
By Lynn Kessler, Don Winar
http://store.yahoo.net/kalmbachcatalog/12240.html
here is a good online article abt faces:
http://www.ww2modelmaker.com/articlepub/GinoPoppe_Faces_article.htm
and another that might help:
http://www.minitaly.com/paolo/guida_faccia_e.htm
try searching google or infoseek for 'painting faces' or 'painting figures'
you will find a ton of stuff.
ed.