Go to the designated meeting area a few hours early to scout. Ensure you note all possible exits as well as any potential dead ends. I also suggest stashing weapons in hidden, but easily accessible spots (bushes etc) just in case things go south.
You've got to be careful with these person to person meetings. Be wary of what physical signals you're sending out.
Don't put your hands in your pockets at any point, for example. It's considered an act of aggression among humans. So have your cash in your hand when you arrive.
Similarly, never blink with both eyes at once - the momentary blindness can trigger a flash-attack from your host. Always alternate eyes.
And smile. for the whole meeting if you can manage it. Maybe practice in the mirror before you go. It helps diffuse any other social faux pas. And maintain strong eye contact.
Take all that on board and you should be ok.
How do you sell a chicken to a deaf man?
DO YOU WANT TO BUY A CHICKEN?