I am just getting out of pretty much the same situation, as you can probably guess by reading the first posts I did on this forum.
In the meantime, after following the advice of many of these fine ladies and gentlemen, I have come to realise a few things...
The stronger your sub is, the greater the satisfaction when she does EXACTLY what you desire (and yes, I have a real tough one on my hands)
What you lack in experience you can make up for in enthusiasm... do what you can do, don't try to be a dungeon master, it comes naturally as you progress.
Your sub claims to be a sub, make her prove it to you... if she/he is acting up, punish her.. be firm, that's what she/he expects from you.
Be creative, as you can learn in this forum (from guys like the great Mobius), you don't need to fork out tonnes of money, just be creative... make your own toys, use them with confidence and conviction.

And most importantly, This is a journey for both of you... regardless of her experience, she has NOT been dommed by you before! you will add your own personality to the mix, you will set and enforce different rules, in the words of old blue eyes... ".... I did it MY way".

Have fun, this too is really important!

Greetings over the oceans

LB