Ok here is an update on the figure I am working on.
I finished the base of the smock the figure will be wearing. As you can see the rough underpinning has now been covered and I added the drapery of the smock. They key to sculpting drapery is to make sure the surface you are sculpting is completely smooth before you sculpt in the folds. This way you don't have to smooth out your surface after you add the folds and thus don't distort them.
The best tools to use for folds are clay shapers -see here- to learn more about clay shapers. Another good tool to use is a pin tool