Do you have any tips or advice for building self confidence in my own ability as a Dominant or is it a case of practice makes perfect?

Learn to listen. Not for a list of keywords that trigger pre-defined soundbites in your head, nor to parrot her nonsense back at her. Listen for the connections. Connections between disparate parts of her life, and between aspects of her life and aspects of your own.

Treat it like a test. Nothing will build your confidence quicker than knowing the material.