As you don't yet know any of the girls it's probably better not to fixate on the line up too much for your first experience. You may have a preconceived idea of what girl appeals the most, but then walk in and fancy someone else much more
Just arrive with an open mind.
Don't worry about the nerves, they mean you are alive. If you don't feel any then I'd be worried
It is a big step into the unknown for any first timer but with this provider you can be confident that there is so much positive feedback that you have no need to worry about them. I was most worried about the safety of my belongings more than the sex when I first went, but all is fine. As soon as I saw my stuff was safe I relaxed and had an amazing experience. You won't start to calm down until you are with your first girl, but then go with the flow and all will be fine.
Parties aren't for everyone, but as smiths says, unless you try it you will forever wonder. If it's not your thing, at least you know. If it is your thing, you will wish you took the plunge much earlier
And don't be afraid to join in. That's the whole idea of the party!!