If you are going to lap on their parts for hours on end, ladies would prefer that you do it in a pleasant manner, so with any kind of rapport at all they will happily share some tips (though there is no one way that will please everyone). To be fair, you also should be ready to hear an answer you may not like, "I would prefer to skip it."
Like poker, there are tells - if she gets wet and seems to be coming almost before you have touched her, the message is "Please stop this ASAP." If she sits there quietly and the only moisture seems to be what is coming from your saliva, the message may be "I will be a good girl and endure this, but it ain't fun." OTOH, if she seems to be gushing, legs are quivering, she is holding your face in a death grip, shoving your head down and screaming, "Don't stop!" she probably likes it. Or she is a great actress. Does it really matter which one it is?
Most of what I have learned, both from published research and conversations with providers that I came to know in a less professional way, seems to suggest that how much, or little, fun, a provider has with you does not have anywhere near as much to do with you as you imagine - she is bringing her own baggage to the party, and if she has to rely on the next client being a good lover to get through it without anguish, she is not going to last very long in this business.
Which is not to say that you should not try to please her, take pleasure in pleasing her, and learn to do a better job of pleasing her, or that at the extreme (say the guy who stinks, has three days of stubble and whose touch is most similar to being battered by an angry Grizzly Bear all the way down to the claws on his fingers, or the guy who looks like Brad Pitt, knows how to read every breath and movement and bring any lady to some non-stop orgasmic state) we cannot make it fun, or very unpleasant for any lady, just that most of the time we make a lot less difference than we think.
Anyway, see someone a few times, get relaxed and ask her to coach you. It works.
zig