Registered mail. Return receipt requested is probably the safest way to send things. Securities and diamonds are shipped this way. You need to seal the item with PAPER sealing tape, so the box edges can be stamped up by the clerk.
.Plastic tape is not for registered.
Registered is the only form of shipment under lock and key. The buyer has to photo id themselves risk arrest. etc etc
Forget insurance overseas with Registered. ...... The buyer should formally release you from claims, IN ADVANCE, by email, should the package be lost. They should say they are aware, as a shipper you are at risk.
(CYA .... cover your a ....)
Paypal is good and convenient, but acts as a shield for scammers.
I ask for a telephone call,and when they call, a call back #,
Assume you are about to get ripped off.
or
learn by experience ....
good luck!