Full Sphag and Bag
For this you need sphagnum moss and a plastic bag.
The function of the sphagnum moss is to keep the humidity inside the bag at 100%. This doesn't require a lot of water in a closed bag. I have used too much moss in the past and that can lead to rot problems. Wring out a small amount of moss and let it air dry for a couple of hours before putting it in the bag.
The plastic bag should be resealable. There are several equally good zipper type bags available. I primarily use the quart and gallon size bags.
Some growers swear by sphag-n-bag, but I rarely use it for anything except cymbidiums. For Cyms, there is no sphag, just bags in a box in the garage.