Be sure not to send any glass containers.
Lotions, creams, wet wipes, etc. must be sealed in ziplock baggies.
Liquids, like mouthwash, perfume, aftershave...are absolutely forbidden, due to the alcohol content. You can't send priority by USPS anything with alcohol content-- it is considered flammable/explosive and can't go on the planes.
Thanks for all the tips. I'm going to check with the gals in the Hobbit Hole who have been sending stuff to get some packing tips and recommendations for stocking stuffers.