Hi Samantha,
I have shipped internationally many times with no issues at all. I only ship via Priority Mail Express either flat rate or in my own box, depending on the size of the item. You may know that USPS does not offer insurance for International First Class mail, so you may want to consider another insurance company like Shipsaver if you decide to go International First Class.
Also, there are some countries I will not ship to. I always check whether the country is on Shipsaver insurance "Prohibited Countries" list that they will not insure. Countries such as Brazil, Venezuela, Russia etc are not insurable through Shipsaver so I tell customers that I am unable to ship to their country.
Good luck!
Anne