I'm in the rather unenviable position of packing up all my majolica for an upcoming move. I hate packing majolica because the body is so soft, the slightest miscalculation and you have a chipped piece. Special care should always be taken with it.
Years of traveling around the country doing antique shows has made me an expert on such things though I hardly enjoy it.
Things I've learned about packing pottery:
1) Never pack plates lying down. Always position them up as if standing on their rim. That prevents any undue weight from cracking the lower plates. Plate edges are remarkable strong while the flat part is the most vulnerable part of the plate. Always allow for plenty of cushion between plates.
2) Hollowware is safest when packed upside down or on it's side. It keeps undue stress from pushing into it.
3) Always allow a 2"-3" cushion at the bottom and the top of the box to absorb any impact. When that carton buckles in from all the other boxes stacked on top of it, you'll be glad you left that cushion.
4) Always pack lids with the base. I learned this one the hard way. I lost the base to a cheese dome at an antique show when the box containing it was accidentally taken by the neighboring dealer's movers. I had to drive all the way to St. Louis from Atlanta to pick it up for my next show, and then the dealer blamed me for inconveniencing him!
5) Regardless of whether it is being shipped professionally or being carried in your own two hands you should never hear any movement when you shake the boxes. Everything should be absolutely solid. If you can hear noise than you need more packing. Remember the post office rule whenever packing: "If you can shake it, we can break it."
Moving is never pleasant but even if I have professional movers packing up the whole house I would still pack my majolica myself, and carry it to my new home with my own hands.