stick to lower subdivision levels for a longer time, because you are getting that trademark blob-look that most people get when they are new to Zbrush, and that is because people see Zbrush and say "OMG, DETAIL", and they don't take time to sculpt the bigger forms.
Don't rush straight to the detailing.
-Andy

("Fools rush in where Angels fear to tread" applies well to Zbrush)