Your concerns about negotiating for more money (called upsell) can be avoided.  Stay away from ladies that do not list their donation rate on their website.  I have followed this practice and have had no upsell problems.  However, do not try to negotiate, the stated rate is the expected rate. Also most ladies will not discuss their rates once the date starts to avoid LE entrapment.  So don't discuss.

Re GFE definitions.  Ask 1000 hobbyists/providers and you may get 1000 different answers. But there are some common expectations.  Look at this link for one explanation. Also, use the search tool on TER, set days to 999 and enter GFE, exact words. Good luck reading and take it easy on your eyes

. . . a reputable, well-reviewed escort (like myself) will have her all-inclusive donation amounts listed on her site.

There are probably slight variations from one provider to another regarding GFE, but read her reviews for an idea of her usual activities.

-And from experiences with other providers to whom I know personally.

If she is a high end provider you should be able to find out what you can expect from TER. If not, back channel a hobbyist in your area that has a good reputation with TER.

All of the ladies that I know will not negotiate money in person. (*most do not discuss money over the phone*) .... your safest bet is to check her web site & research TER.

In regards to the question about GFE, I think the term generally describes a lady that would leave you with the impression you had spent time with your Girlfriend. I am sure individual experiences may differ but I think that if a provider is a true GFE you will have an encounter and leave with the same impressions. (*That of having spent time with an old girlfriend*)

Have fun, play safe & know your provider... kisses ~Tori

is usually accurate and an added benefit is that you will pretty much know what you are in for before you contact the lady.

Renegotiating prices upward after you meet in person is called "upselling", and is a major red flag.  Reputable, well-reviewed escorts won't do it; a great many won't discuss money in any fashion once you meet in person.

The only time I'd ever expect to have that sort of discussion with a lady would be if I was asking her to stay for another hour, or if we decided to include an activity that wasn't part of the standard experience, like bringing in another lady, or videotaping a session.  (Side note: Many ladies will freak out if a new client mentions videotaping, assuming that he's somehow already taping them.  Given how inventive some pervs can be, they are justified in their freaking-out.)  

Don't bring these kinds of things up with someone you've just met for the first time; once a lady is convinced you're not either a cop or an axe murderer, she'll probably be a little more willing to discuss what her limits might be for a session, and what sort of compensation she might find appropriate if you want something a little different.

There isn't a set definition of "GFE" or "PSE", but it does generally include kissing and BBBJ, although covers are sometimes required.  FS is understood, and different ladies have different rules about multiple "shots on goal".  Misty Bay had a pretty good definition in her response in the "What is Greek?" thread two posts up from this one.