What are you trying to send? If you are sending liquids, make sure the lids are tight, and you put some tape on top and the sides so it doesn't come off. You can also put the liquids inside a ziploc bag and in that way, if the product spills, it won't damage the integrity of the box (thanks BigAl3!) Make sure also the package has enough dampening material (packing peanuts, newspaper, etc.) so the ride is softer.
That's all I can think of right now. Hope it helps...
Joey
