Antiques are a little out of my line. I'm getting to be an antique myself, so I figure that I've got enough. (Grin)
We sell a good volume on eBay (5,000+ Nintendo games and accessaries in the past year) and actually get a surprising volume of business from overseas. Australia, New Zealand, Singapore, Japan, and mainland China is where we do most of it in the Far East, while it's primarilarly the European nations in the other direction. There's a trickle from South and Central America and a flood from Canada.
Most will email in advance and ask the S&H for that country for whatever they are interested in. I'll check with the USPS Postage Calculator that's online (http://ircalc.usps.gov/), add about a buck to cover the cost of our packing materials and a 30 day guarantee, and quote that figure to them. We also mention that there is a big discount for multiple purchases, as we can combine shipping. There are very few complaints.
It's really not that difficult. It's my hunch that most people don't get into it due to the fear of the unknown. As a result, many will discourage overseas business by charging more "just to be safe", if you follow my meaning.
As far as sensible trading tips, here are a few generic ones that may help. Of course, the field is so huge that a specific question may be more productive.
1. Keep in mind that 75% of the bidding will be done on the last day. Most people don't want to bid too early, as that tips off others that they are interested. This doesn't mean that the other days are wasted, as that's when people discover the auction and click the "Watch this item" link. When it gets short, then they bid. I've had things climb over $50.00 in the last minute!
2. You may wonder if something is worth listing. One way to get an idea of an item's value is to type its name into one of eBay's search bars, and when that comes up, look on the left hand border of the page. You will see the link "Completed Items". When that comes up, you will have a list of all the similar items that have sold in the past 30 days, along with the prices they went for.
3. Be careful how you construct your headers for the listings. Don't put in such words as "Cheap" or "Rare". Put stuff like that in the descriptions. Put words that people will enter in the search bar when they are looking for that product. Put as many as you can think of that are related to your item. Abbreviate connecting words like "w/" instead of "with", for instance. This will increase the number of people who discover your auction. The more people, the more bids. The more bids, the higher the ending price.
4. Be very careful about your spelling, especially in the headers. To understand what I mean, put "Nintendo 64" in the search bar and see what comes up. Now try it again using these misspellings: "Nitendo 64" and "Ninetendo 64". They will be there, but in fewer number. Not many people will find them, and they will go for lower prices due to that. (Which is a good hunch for prospective buyers!) (Grin) Also watch the little things. You will get different results for "Princess Diana doll" than you will "Princess Diana Dolls" or "Hummel Redheads" than you will "Hummel Red heads".
5. Don't control your payment methods too tightly. Many if not most new ones don't have PayPal and don't know how to use it. If you accept only PayPal, that eliminates about half your prospective customers right there! Many others, including some very experienced ones, don't like PayPal and won't use it.
We have good success by accepting PayPal, money orders, and personal checks. We ship within hours of getting a PayPal notice of payment or receiving a money order, but we hold up shipment for a personal check for about 10 days after it is deposited in our bank. We've only had 2 bad checks, and one of those was eventually paid.
6. Don't allow the idea of an eBay store bother you. They are simple to set up, and is a central place where people can go to see everything that you have on auction. This encourages multiple purchases. One Canadian gentleman bought 73 items to be shipped all at once, and once they were received, promptly ordered another 26! The links are automatically listed on all of your listing pages, and you are given a standard online address to refer others to. Here is ours, should you like to see what a store looks like. (http://www.stores.ebay.com/id=68775048&ssPageName=L2) At the moment we have about 140 items in there.
Hope this helps!