what I have gotten custom to is to use clay tubes brush a lot in the beginning to shape the volume and the mussels …
I then use smooth brush to smooth pretty much everything out… but I still keep most of the muscle lines…
then I go over with a standar brush with a sharp alpha brush to get the depth between muscles…
then I use inflat over the muscles get the lines out even more clearly.
I hope any of that made any sense to you… its basicly the whole prosess… not just the scetching…
I made a youtube video displaying how I sculpt… just for fun… and I added myself there, to make it a little more personal
it goes at 400 % speed… but you should get a better understanding of the scetch prosess from that …
http://www.youtube.com/watch?v=UpLzHFft-ZM
and a turntabel
http://www.youtube.com/watch?v=E4xqyFRW4ug&feature=channel
i hope this is of any use to you or others…
or you can watch them at my homepage