I've been trying to follow around with the other tutorials out there, and I can't use symmetry (drawing with symmetry across an axis) on zSpheres and its really annoying me. any tips?

Thanks in advance.

dont know what you are doing exactly, but for symmetry - try hitting "X" key.
2. if that doesnt work or looks somehow strange - may be your model (object) is OFF center!

(try bring it in Maya (or other program you use) with Goz Button, POSITION it to the absolute middle of the grid and Goz back to Zbrush)... hope this helps somehow.