The information is intended to help you understand the basics of buying safely, and shouldn't be considered legal advice.
Always review a seller's Instagram account and read the entire item description carefully before you buy.
By asking questions via Whatsapp you get a good feeling about the seller before you make a purchase.
Always use a safe payment method to complete your transaction. The safest payment options are PayPal or credit cards for those sellers who accept credit cards directly. (The seller will never see details about your bank account or credit card when you use PayPal.)
Not all sellers accept PayPal or credit cards. If a seller doesn't accept these, then personal checks, cashier's checks, money orders, and bank-to-bank wire transfers all provide reasonable levels of safety in most transactions…but they don't provide as much protection if you don't receive satisfactory goods. The most risky forms of payment are cash and "instant cash transfer" services like Western Union or MoneyGram.
Double check the list above one more time just to be sure.