For some guys that means $800-$1000 but to others it may mean $500-$600. So start there.
As for advice being new, only see girls with many reviews spread over some bit of time. So while that is difficult to define as well, I would say somewhere in the neighborhood of 15-20 (or more) reviews spread out over a year or more with some of them being recent i.e. in the last few months or so.  
Then look at the number of reviews each reviewer has. Then reach out to them and ask them about the girl in question.
There are some red flags for me. For example, a new girl that has perfect reviews over the last 3 months and all her reviewers have only one review. It doesn't necessarily make the woman in question a fraud, but it should steer away anyone new to this lifestyle imho.

If you search the NY Ad Board (or other Ad Boards), include "Newbie" or "Newbie;friendly" in the Search for [newbie] or [newbie;friendly] field.
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Sometimes "newbie" refers to the Provider ("I'm a newbie to visiting NY ...") or something else, but it's a start but you'll be able to figure out the ones referring to seeing newbie clients.

Newbie

Welcome to this wild crazy fun world. I think setting a idea of what you want and what your budget is, is a great first step.
Personally if a gent cant get through the screening because they are new, I like to grab a drink before hand.  
I tend to steer my friends  away from bigger agency because they tend to be more robotic, but YEMV.  
I hope you have a great first time on the darkside. ;P