Know your geography. For example, what problems are typical where you monger? In the city where I live they are going after serious drugs, guns, and violence. They are likely not going to go after a low profile provider.
That being said, you’re going to have to look out for scams. Is it a bait and switch? A guy trying to set you up? Or, someone who is just unreliable and won’t show? This is part of the hunt, and after doing it a few times you will be able to sense what’s going on fairly well. Note: that if you don’t trust your gut instincts it is always a bad move.
Usually, you go to the location. Say you are there. Provider gives you the room, and they are already dressed skimpy, if not nude, indicating it’s legit.