Never done this before, but reading from many articles I can conclude some points :
1. Refrain from feeding your fish 2 days before you bag them for live shipping.
2. Place the fish in 1.5 to 2 milliliter plastic bags
3. Fill the bag with the minimum amount of water necessary.
4. Label your box inside and out and ship immediately after packing.
5. Call your customer and let them know when the live fish will arrive so they can make arrangements to receive and open the shipment immediately.
6. Insulate your shipping box with polystyrene thermal insulation and packing peanuts