Def a public place. I have even heard of dudes meeting outside a police station to ensure complete safety from both parties.
Also make sure you go with someone. Do not meet alone. Honestly bring as many people as you can. I'm assuming these are for Yeezy's which is a shoe you'll prob be paying top dollar for. So the more people you have the better.
Another thing is don't take out the full wad of cash right when you see him. Try and inspect the shoe fully before you let him hold the cash.
Just be smart and safe about it. Also you should do a legit check on the person if possible.
Hope this helps... idk if this is just all obvious stuff I've lol.
if i was meeting someone and i seen a bunch of dudes i'd think i would be the one getting robbed. bring as many people as you can? really?