I don't know who is Thomas :)
Modelise a very realistic face in Nurbs is possible but very hard!
take a look at this ;)
http://www.youtube.com/watch?v=x_bqn609mSs

Today it's very more easy if you are an artist to use something like sculptris (Free)
http://www.sculptris.com/ sort of Subdivision polygonal modeler very easy ;)

http://www.youtube.com/watch?v=MgHfDsIcqR0&playnext=1&list=PL8963E19AF0532B23