When I first started shipping plants I was only guessing as to how to do so.
Things I have tried:
1) Since one of my first trading partners was Copper, I emulated what she was doing, which was wrapping the plants in moistened paper towels, in a baggie.
2) Then I tried other things. One was to ship them in 50 & 100 ml tubes, with layers of wadded paper towels of plants.
3) Then I tried the Whitman Sampler approach, which was to use one of my plastic pipette containers, with the plants planted in various locations, and a paper showing what and where it was.
4) Recently I tried placing plants in moistened LFS, in those arts & crafts bags.
5) A couple weeks back I received a few sundews from Capslock. The planst were nestled in the bagged LFS, moistened, and placed in a baggie. Now I'm used to sending and receiving sundews that lose their dew, by the time they arrive. These sundews still had their dew! I was very impressed. That was the best shipment I had ever received.