Most encounters for me happen after a long day at work and up to an hour sitting in L.A. traffic, so I'll usually request a shower on arrival. At the very least I make it habit to bring a travel-sized toothbrush/toothpaste combo and a pocket back of flushable wipes. I'll ask to use the bathroom then brush my teeth and do a quick wipe down of the "strategic" bits.
I find that ladies appreciate the effort and sessions tend to go better, especially the oral parts, when you make the effort to have fresh breath and a nice clean scent instead of smelling like gym shorts and whatever you had for lunch.
You will get much more enthusiastic service if you shower there just before you get busy with her. She will know you are completely spotless and will not have any hesitation about putting her mouth anywhere on your body. Use the first 5 minutes of your hour to shower (and invite her to join you) and the next 55 minutes will be the payoff. A co-ed shower is the best ice-breaker there is with a new girl you are seeing for the first time. Initiate a little playfulness and its sets a good tone for the rest of the session. Once you learn how to use the shower to get things rolling, you will never want to take a session without it. Trust me on this. If you tell her you showered an hour ago, the first thing she will think is "but then you stopped and pissed before you got here." Even though the LEVEL of clean may not be any different in reality, its still may be a psychological hurdle for her.
He put down the $$$$ and went to shower so she can count it and put the $$$$ in safe place
Out of site out of mine.. and then the show starts ..
...I also bring a few flavored personal wipes with me. I get them in small packets that fit 2 or 3 in my back pocket. I offer the packet to her just before she starts any oral fun. And keep an extra I can use on her when needed - which is rare, but always better to be prepared.
I find most providers appreciate this as a sign of respect and it reinforces my meticulous hygiene. Next, the flavors (cherry, mango, etc.) help keep the fun well... more fun. 
In addition, to ensuing our session will include specific acts that I want (it's all about mutual consent!), intimacy and enthusiasm are the two most-important qualities I look for in a great session. Adding some small gestures that can make her more comfortable are always a good investment.
Life is good
The Cat