It never ceases to amaze me how poorly most people pack the watches I buy in - or how often the watch actually survives, I have a strong suspicion that watches gummed up with old oil are more robust than a newly restored one, which is rather annoying!
The main problem I find is that where people go further than just putting the watch into a jiffy bag (or envelope!) they tend to protect against crushing, against which the watch is actually quite resistant, rather than against shock which is the bigger risk. They also tend to wrap lots of tape all round the watch and / or packing which contributes nothing to its safety and by making it difficult to unpack increases the risk of damage after it has arrived.
I started off packing watches in a small box wrapped in bubble wrap in a padded bag, over time I used more wrap and a bigger bag then replaced the bag with a cardboard box which although more expensive did, with the elimination of sticky tape, turn out to be quicker to pack and I suspect also discourages rough handling.
Here is the latest and hopefully final version of my packaging. The watch goes into a jewellery pouch and the pouch into a sealed plastic bag to protect against condensation particularly if transported in an unpressurised / unheated aircraft hold which frequently happens even on shipments within the UK, although international shipments present the bigger risk.
Then into a small but strong cardboard box with padding top and bottom. Annoyingly the boxes come with just one bit of padding so more has to be added.
Next into a medium sized box with a lot of bubble wrap.
Ready to go except for the address label and packing slip.