I've shipped internationally before. Had aboot 50 or so international sales. Mostly to Canada but some orders were all over the place, France, Spain, Brazil, Russia, Malaysia.
I used Stamps.com, I believe you have to wait on line if you don't use Stamps.com, Endicia, etc. It's easy with postage printing services, addresses and customs all on one printout, no need for filling excess customs forms or sticking envelopes for them.
However...
It was basically a high risk for me since I shipped out things either using First Class International or Flat-Rate International. Buyers overseas were willing to pay more since the S/H was fairly cheap to them (It costs pretty much the same to ship First-Class International as is does for Domestic First Class). I lucked out and had no problems.
After reading some international shipping horror stories I have stopped shipping internationally unless the buyer is willing to pay for more expensive shipping options with 'true' tracking and confirmation.
Delivery Confirmation is useless overseas, they only scan it when it reaches the post office or leaving overseas or sometimes never. They never scan it when it is delivered.
After a few times when USPS did not scan my international packages, I made sure to bring them to clerk even if they were pre-paid and made sure they scanned them and I had a receipt for them.
It turns out that in eBay's eyes, it does not matter if you have proof of sending, you need proof of delivery.
So if you plan on shipping internationally and want profit, make sure the item is high demand overseas and that buyers are willing to pay for more expensive options.
If you plan on shipping internationally, don't go with First-Class International or Flat-Rate International despite the temptations of cheap S/H. It may come back and bite you in the butt.