I've had ZB for over a year and I still pretty much stink at it. Mostly due to not having enough free form practice time.
For now, I'm just tackling stuff I can speed sculpt do during lunch. Here's a half formed doodle of one of these steroid cases who's way too jacked. It represents about 2 hours worth.
It could be better. I know. I just need to find more time outside of my poly modeling.