Suggestion for modeling

 From:  Andrei Samardac
Hallo everybody, for long timae have no post here, experimented with sculpting in cinema 4d.
And have one question, I have made this skecth of space-marine, and want to transfer it to nurbs. But have no Idea how to start and what approach to use.
I'm Intrested in hard surface this organic stuf on the stomach will sculpt latter.

For example this shoulder how to model, have no idea how to start e.t.c...)) Any Idea would be greate)