I'm now sold on ziplocking cans.

I bubble wrap or dense foam everything. I try and line the box with xtra cardboard. Sometimes I wrap in baggies sometimes not. For special bottles I've double boxed the whole thing, only running it over with a truck could destroy it. Just depends, but lots of foam and peanuts are a must both for protection and noise reduction.

 

I always err on the side of extra packing when shipping beer. Bubble wrap is a must for everything - cans and bottles. I also have learned some tricks from my last trade, and will add ziplock bags to make things even safer.