Look under "My Information"-->"Conditions of Sale" and "Parameters" for the boxes to check for standard messages to leave.
You can also write whatever you like in the 'message' box within "My Parameters." Many charge a fee to the buyer if paying by Paypal or Moneybookers, say. .5 Euros or 2% isn't rare. I prefer to charge a flat S&H for buyers: $1.50 for US address, $2 to Canada or Mexico, $2.50 everywhere else. I ship in rigid postcard sleeves and this covers their cost and postage and Paypal fees in many cases; if they're paying me overseas and it's more than $50-100, well, the Paypal fees aren't covered but then I have a nice sale to make up for it!

It seems that wire transfer are the norm in Europe, France anyway, but it's too costly for US banks. Oh, and you can specify currencies you accept in the message as well; same for "domestic checks only" if you take checks.
Check out what Scview has in his message for example; or copy mine. You can go 'all out' and translate your message into 5 languages if you wish or just keep it in English. It's really nice in that you can specify/accept/decline to accept nearly anything.
Welcome!