The best way to sell your originals is to go through your bank with a IBAN or SWIFT number. The money is paid direct into your bank and you can phone up your bank to check it is there. The buyer cannot withdraw it again and they have no idea of your personal details.

NEVER pay money to a buyer in any differences, EVER. They have to pay money to you and so that should always be the exact amount. Not a penny more or a penny less.

NEVER allow them to ship the product, ever. You need to know it is insured up front and you need to keep all receipts of shipping. PLUS always get the shipping that has to be signed for by somebody at the other end as proof that someone received it.

If using PayPal, always move the money out of your account into your bank account before sending anything.

NEVER follow an email to PayPal whether before, during or after. You should always go to your bank online, PayPal online, or any other financial establishment by typing it in your own address bar. NEVER follow a link.

Remember, if an email can be sent, it can be forged.

IBAN (UK) International Bank Account Number
SWIFT (USA and INTERNATIONAL) What Is a Bank SWIFT Number?
PAYPAL SAFETY ADVICE + Disputes

If in ANY doubt – ASK SOMEONE.
Never ask the buyer, go direct to Paypal or your bank who will happily give you advice for free!