Keep poly count REALLY low until you get the general shape. Then work from there, grab some of Jay or Kurts tuts to get a feel for it. Organics are hard...can you get any more reference images so you can rotate the head to a front on image? that would make life a lot easier.
cheers bullet
bullet1968
"A Darkness at Sethanon", a book I aspire to model some of the charcters and scenes