Clean your sofa with leather cleaner and conditioner and a lint-free cloth before storing the sofa. Leather conditioner can be purchased in most hardware stores and some stores that sell furniture as well as through numerous online retailers.
Remove the legs from your leather couch with an electric drill or screwdriver if possible by unscrewing them from the bottom of the couch. This will help prevent the legs from being damaged if the couch falls while moving it or while in storage. Store the legs and screws in a waterproof plastic bag to prevent water damage. Removing the legs from your sofa will also help you save space in your storage area.
Wrap the body of the sofa in waterproof plastic that will repel moisture. Tape the waterproof plastic to the bottom of the sofa using painter's tape that will not disintegrate and stick to the plastic.
Stand the sofa on one edge on top of a wooden pallet or elevated surface to prevent moisture damage and to save space in your storage area. Concrete, which is a common flooring surface in storage units, can easily become damp, damaging your furniture.