I've had the good fortune to work in places that ship expensive stuff frequently. One of our packers gave me crap for how I packed a personal package (I was young and naive), and he demonstrated. His wisdom was "if I can't stand on it, it won't make it".
SOP was lots of paper around the item. Pad the box well, wrapped item in the box, pack the box the rest of the way, then wrap the box in paper, second box gets layers of crumpled paper, first box into second box, pack with paper, crumpled over the top, lots of tape. Anything long and slender or sharp edged got its own attention with paper, foam, more cardboard, etc. Often, the second box got a separate layer of cardboard over the bottom flaps, and another on the closing side. If there are small parts, the first box goes into a trash bag in case of a breach.
Overkill is best kill. Also, we never had a claim denied, and damage was rare unless it a forklift punched it or ran it over. Some of these packages would hold tens of thousands of dollars worth of parts, so they tended to be careful.
Also, clear tape over the address or pack slip because that stuff blurs when it gets wet! We'd also mark the street name and number on all 6 sides. Helped more than once.
