Honestly, my advice is to not worry about it up front, and dive in.
You need to worry about making your first sale (which is seriously, very hard), long before you worry about returns. =)
You'll figure out it when you need to.
Depending on the shipping company in use, there may be local returns addresses in some countries that will get on forwarded, or it may be worth it for you to set something up.
Assuming you are upfront about the product coming from China I don't think it is too bad to get them to send back there, obviously in some cases a customer won't be happy and you would offer to cover the return on a case by case basis.