ZBrushCentral

This Is My First 3D Sculpt, Where Do I Go From Here?

This is my first 3D sculpt, I watched YouTube and read articles about Zbrush relentlessly while I was waiting for my tablet to be delivered, installed ZBrushCore a couple days ago and worked on this for the better part of today. I’m quite happy with it as a first work but I would really appreciate advice/critique on how to continue working on it.

Where should I be focusing my efforts to make this sculpt better?