The shipping method I use for items from my offer is Registered Priority Letter option from Polish Post (Poczta Polska).
This option is rather quick (takes 14 days in most cases, but International Postal Law doesn't oblige mail handlers to any deadlines) and safe.
I receive a shipping confirmation few days after dispatching the item and it contains a tracking number which is possible to track in many countries' postal service websites.
Registered mail means that the buyer, or an entitled person from from his or her house will have to sign for the packet before postman will hand it to the recepient.
In case of a failed delivery, when nobody could sign for the packet, the postman is obliged to leave a note and usually takes it back to the local post office where it can be picked up by the recepient (name, address of delivery or tracking number will suffice) within a month (depends on the postal service, but the month is the usual time the post office will hold the packets until it is returned to sender).