Artists advice wanted on how to post painting to USA and paypal

[Minitoots]

I have to send an unframed painting on paper to a client in USA and haven't shipped/sold overseas before so wondered if anyone has suggestions of courier companies to use where shipment is tracked? I usually use 'interparcel' but thought it would be good to know of any others. I plan to send the work in a strong tube.

I was also planning to use Paypal and will post the work after receipt of the fee - does this sound the best/most secure option? (Obviously I have checked the client out and got references etc...)

[Phlox]

Royal Mail does an international tracking route. I have sent something to the US that way, but not a painting. Or try DHL.