paypal. first class air mail. make sure he/she knows the risk is theirs, no insurance. keep receipt in case of problem. keep customs number for tracking.
For high value ship EMS with tracking number, or UPS w/ insurance.
cover yourself each step of the way; whatever the customer wants keep documentation as customers have selective memory. Most people are ok. ASK PLENTY of questions if necessary as this will flush out the scammers. good luck.
EDIT: stay away from third world countries -- too many problems and corruption. big time risk.