I can help... since all I do in school is draw snakes and keep an A average..
What I do is I just cross lines all through the snake or simpy draw small semi circles... it's pretty easy. I might post a sample if I can find one...
Oh btw, if you go to a library and go to a section where they have drawing books (probably in the kids section) and find one that shows snakes or reptiles they discuss how to do it.