Hi,
I agree about USPS Priority Mail Registered with insurance.Note ALL above "services."
As far as packaging -
1. Try to use the original thin film watch head protector that came with the watch. If you don't have that anymore, most high end brand AD's can supply you one if you ask nicely.
In the absence of this, a TIGHTLY wound saran wrap could work, but there must be NO play between wrap and watch head.
The concern here are micro scratches, usually manifest as spider webs and swirls on the high polish areas.
Also, not all plastic wraps are equally good or safe, some actually end up being the cause of clouding or scratches themselves!
Do same for deployant or buckle if possible.
2. Then place the wrapped watch head and strap/buckle into a plastic bag - baggie or kitchen Heftie bag or equivalent will do, ideally with the watch and strap wrapped around a cushion or pillow to prevent deformation or damage to the strap (a high quality OEM croc runs $400 to $800 USD!)
3. Place the watch, pillow cushion, inside the plastic bag, all inside a small or medium USPS or UPS or FedEx box, stuff with packing peanuts, air pillows, or bubble wrap so there is as little motion inside as possible when the box is sealed. It doesn't have to stuffed to the gills and all contents under pressure, just no rattling around.
4. Place this sealed box, fully addressed with both sender and recipient info, inside a large USPS or UPS or FedEd box, add packing material and BE SURE all addresses are correct.
WARNING - BE CAREFUL about insurance offered by common carriers like FedEx and UPS - they specifically EXCLUDE watches and jewelery and the shipping clerk often doesn't tell the lay shipper of this exclusion because they don't know themselves.
If you need to ship box and papers, same ideas apply -
Protect the papers so they remain as flat as possible.
If you ship the watch inside the original box (I personally don't advise this) make sure the watch is wrapped so the watch head doesn't rub directly against even the soft inner linings of the box, for both the watch's AND box' sake.
And make sure the watch is secure and not loose, "rattling around" inside the box, even the original mfg box.
And never a bad idea to double box-you pay a little more postage for the weight but worth it for peace of mind.
What if the package unexpectedly gets soaked?
Or sits under 500 pounds of other packages or mail?
Packed as above your watch should be safe from handling damage in 99% of situations.
The courier airplane going down into an ocean falls in that 1%.
Hope that helps.
TM