I was chatting about how to do realistic looking eyes in ZBrush recently and I realised the method I used was one I saw Pixolator (Mr. ZBrush himself) using back in about 2000. I decided the quickest way to show my work flow was a little tutorial.
In this video, I'm showing how to make polygroups in ZBrush using UV mapping. The main advantage here is that it's far more accurate than using for instance masking, or hiding parts and making groups that way. I do this for every character I make, and I always find to be very helpful at some point during the sculpting.