Basically you want to wrap the plants in damp (not soaking wet) paper towels or newspaper. Then place these into an appropriately sized ziplock bag. Place all the bags together in a box that has been well padded with crumpled newspaper, styrofoam, or the like This will keep the plants from being bounced around in the box and insulate against temp changes. Include a heat pack or ice pack as weather dictates. If you're shipping within the US, USPS Priority usually gets plants there within 2-3 days and is realatively inexpensive. I've used this method many times, and so far plants have always arrived in good shape.