I emailed a provider asking her a question if she'd be in my town. She replied saying she would and that I could either call her or leave my number to set up a session. Now I don't have any references with this being my first time so my question is what should my next move be?

Should I just call her or should I email her back leave my number and explain to her that I'm a newbie?

make sure your communication method is private.  I like e-mail but your choice.
skb

Be honest with her about your references, and ask her if there is any other way she can verify you are a good guy.  She probably has other ways of approving clients.  If she is an experienced provider, she will know how to verify you in other ways.

So, be prepared to give her employment info.  She can call your office, ask for you and verify that you actually do work there and are not LE.

Bottom line is, go back to my first line, be honest with her.  Chances are you are not the first noob w/o refs she has seen, especially if she has a lot of reviews.  So she will know how to handle your situation.

Swim

...volunteer information. There is always time to tell her you're a newbie and/or give her work info or whatever she needs to feel secure.