For your information, it's always better to do it online. However, if you do it in person, be sure that you are using PayPal Goods & Services: 
We recommend you use Paypal or any other payment provider that can guarantee buyer/seller protection. In case you bought a counterfeit product, you can open a dispute so Paypal can choose if you are entitled to get a refund. There are some fees for using this method, but at least you will be protected. Only use Friends and Family with people you know in real life.
Then, meet up during the day, in a public and safe place so you don't get robbed. The only advantage to buy items in person is you can check the quality, so you can bring your legit checker (but agree about that with the seller before).
NEVER use cash. Not only can cash be stolen very easily, but once you give someone cash, it's gone, and there is no way of charging back or opening PayPal disputes. It's gone for good. If for whatever reason the seller requires cash, ensure 1) they hand over the product first 2) you have the product authenticated prior to meeting up or you do a detailed authentication when meeting up with the seller. Only after those 2 steps should you hand over cash (if you have to use cash in the first place).
Just like with cash, you should avoid apps like Venmo, Cashapp, Zelle, and wire/ach transfers as just like with cash, once you make a payment with one of those methods, it's gone and there are very few remedies available to charge back or dispute the transaction.
Need any further help? Contact us.