I wrap with bubble wrap and then use peanuts to fill all the voids. I also tend to slightly "pack" the peanuts so there's no movement.
If you're packing, and you think you're done, hold the box closed and shake in all dimensions. If anything is felt moving, you're not done packing. If it moves inside the packaging, it likely beats itself to death during shipment! Whenever I get a repair or upgrade, I do the shake test. I cringe when I feel it moving to any significant degree. I also frequently find broken stuff when I open such a box!
Remember, even in the factory packaging, you may have to add some additional padding to keep it from moving.
