Most of the watches I work on are family heirlooms, priceless to their owners. It's not easy to ship something like that for fear of loss or damage. That is perfectly understandable. No shipping is risk-free, and if this is something that will keep you awake at night then you shouldn't do it, simple as that.
If you decide to ship a watch, I can say that I have never had any trouble. Here are a few tips that greatly improve the security and safe delivery of your package.
1. I have always used USPS Priority Mail. The Post Office provides standardized boxes for Priority Mail free of charge. I use their medium-size square boxes. Include padding such as foam peanuts, and wrap the watch individually in foam, bubble wrap, or something similar. Placing the watch inside an inner box is nice for added security.
2. Place a note inside the package with your name and address.
3. Address the package clearly.
4. Ask the clerk at the Post Office to stamp your package "Fragile."
5. Insurance... I'm frequently asked how much to insure a package for. This is a hard question to answer. The actual replacement value of a watch is one thing, but this isn't the point. Nothing could not make up the loss of an important family item. The amount of insurance, therefore, is something that has to be left up to you. I receive many packages with no insurance, and that is fine too.
6. Email me when your watch is actually on its way. I'll be looking for it and I will let you know when it arrives. USPS Priority Mail takes 2 to 3 days.
One last thing... Pack your watch while it is not running. A running watch has a slightly increased chance of being damaged by a sharp, physical jolt.
If you like to use a provider other than the USPS, such as UPS of FedEx, I have also never had any trouble with these. And I will return your watch by the same method.
Again, I have never had anything turn up missing, or damaged, in spite of mailing things out and receiving packages every week. But if the risk of shipping bothers you, then you really should not do it.