During our lessons with Leavon he taught us a whole range of different utilities avaliable in Zbrush and was an amazing help. I also did several tutorials during the course of the module to upgrade my knowledge in Zbrush as I hadn't had much previous experience.

One of the tutorials was just the basic editing and different brushes, this helped me get started and was a good reference point - http://www.youtube.com/watch?v=6-hRle7SpyA

I also learnt a lot from Mike Jensen's tutorials about hard surface modelling -
http://www.youtube.com/watch?v=_xOKVGbZmEc&feature=related


I also watched a lot of speed sculpting to see how people get the shapes and what brushes they use for certain effects, I found these of great use and were really amazing to watch.

http://www.youtube.com/watch?v=1uPwNZW1gRk&feature=related

http://www.youtube.com/watch?v=9Adjg2oVDbI&feature=relmfu

Stephen Fry - Zbrush