You really have to be careful of a few things.
First is Law Enforcement. Never, ever, ever discuss activities and money. Questions like "What do you charge for a blow job?" is solicitation and that is enough to get you arrested if it's a sting. So just give her the money and keep your mouth shut. Once she starts with you, then you can ask for a whatever, but never in the early stages. While this approach will protect you from a conviction, if it is a sting, they can still haul you down to the Cop Shop, question you for a while then make you call your wife to come pick you up. So there is still some real risk.
The second big risk is getting robbed. Go in with your eyes open. Get there early and park and watch who's coming and going. Take the agreed upon money with you and leave your wallet, watch, phone, etc. locked in your glove box in your locked car. If you can, take a look around the place when you arrive. If it's a motel room, tell her you need to wash your hands and make sure you pull back the shower curtain. Check the closet. Throw the deadbolt and the chain on the door to keep others out while you're there. If she's uncomfortable with any of this, it's time to leave.
The third is an STD. I'm amazed at guys who will do a bbbj from a high volume provider. Listen to your high school health teacher and wrap that rascal!
Finally, if your gut is telling not to go, then don't go. Wait until there are some reviews and go from there.