Hey there, the safest way is to purchase a small pet carrier at walmart (less than $20) and send them via Delta Air Cargo's pet first shipping. This can be rather pricey though. Another way is to pack them in a Styrofoam lined box and send them via a carrier such as Fedex. (use heat packs if they will be traveling through cold areas) Here is a good link showing how to do it this way. http://www.chelonia.org/Articles/shipping_chelonia.htm
Also if your working out a trade with someone, its always best if they ship to you first. Once you receive their animals, inspect them and make sure they are what you are supposed to receive. If everything is OK, then ship your animals out.
If you dont have a shipping account you cant write what its the box on the box. Usually people will write *Perishable* on the box or something like that. its a pain to get certified to have fedex ship live reptiles.
Delta lost one of two shipments I had delivered that way. Had to meet the plane, where as the others come to the door. Also means longer the animals are in their care or perhaps lack of it. With the lost animal they found him about an hour later. He had been left at a stop. They actually had someone bring him to my home...which was 2.5 hours away from the airport.
UPS man was great all three or four times.
DHL I have a bad guy who fails to knock when he brings the torts. Have used them the last two times.
All animals by all (except the one plane) have arrived by the next afternoon and in perfect shape.
Delta dash is good if you have a large tort or something that is very expensive that you want to be (for the most part) taken well care of...
UPS/DHL are what I normally ship stuff with, just depends on cost and what the buyer wants... Do the overnight early next day, or normal overnight depending on what you ship and temps... Pack to what the temp is as well... Hot? add a cold pack. Cold? Add a heat pack... Ect...