The art of getting a woman to orgasm in my opinion is to get her to relax. If you charge in there and either try to fuck an orgasm out of her or DATY her aggressively then you will probably fail.
Girls appreciate gentle customers. Smile at them as they say hello, talk to them as you walk to the room with them, compliment them, hold their hand. In the room sit them down and talk to them for a couple of minutes, put them on your lap, kiss them, caress them, shower with them.
Once you have done all of this the girl will know that you are not just another wanker wham, bham thank you Ma'am customer and then she will relax. Take your time and make love to her. Kiss her, touch her erogenous zones to get her warmed up, stroke her skin, massage her softly. All of these things will help you get her to a state where she wants to make love to you and not just service you like a "normal" punter.
DATY is a slow build up. Girls like it gently and then you build up the tempo in tune with their bodies rhythms. You can feel what parts of their pussy they respond to the best by slowly exploring the hole, the lips, the clit, what part of the clit responds the best. Once you have found that sweet spot then try and concentrate on that as the girl rises to an orgasm.
That is what works for me. Oh and book them for one hour. Anything less is too short to make love to a girl.