Every scenario is different and depends on the personalities involved. I'd say, first, check her out on TER to find out what she does as a provider [if she's not listed, then you're rolling the dice]. You'll know if she's incall/outcall and her usual donation rate before you talk to her. Then, when you call her, let her ask you the questions; don't bring up sex or money...just set up the date. When she shows up, follow her lead and just be yourself. I usually let her tell me what she wants me to know and I don't haggle or give any donation up front. If it doesn't feel right, I'll bid her farewell and spend the night whacking off to a good porno. If you're a newbie, she'll know it. If she's any good as a provider, then she put your mind at ease and walk you through it just fine. Whatever you do, don't try to follow some script or be an asshole.  

Ultimately, YMMV (YOUR MILEAGE MAY VARY), so prepare to live and learn. Good luck.

This post will probably get some dissenting opinions, but here’s my couple pennies worth.

First, do your research as Blakkromeo2k says:  read the reviews, read her web site, etc.  Learn what you can before you talk to her.

In the phone call, you are unlikely to get your questions of specific acts/costs answered.  they are in the reviews or her web site.  Instead, focus on where/when, how long, and most importantly, does she sound like someone you would like to be with OUTSIDE THE BEDROOM.  You are likely to be nervous at the start, but can she make you feel comfortable with her conversation?  You will likely be MORE nervous in person, so this is important.  What relaxes you isn’t the same as what relaxes her.  Do you get a sense that she is unhurried in the conversation, even if it only lasts two minutes?  Again, you should be feeling out perceptions, because most the best Ladies exude wonderful perceptions FOR YOU.

Let her know you are new at this.  If you accidentally do something that would offend her, she is more likely to overlook it.

If she says something in her web site about how to pay, FOLLOW HER GUIDELINES.  If not, I find that a plain envelope attached to some flowers usually works very well.

At the meeting, start out being yourself as you would be when you go on a first date with any beautiful woman.  Complement how she looks, etc., she has probably worked hard to get ready for you.  Let her lead the first dance.  Relax and enjoy.

PM me if you want.