In order to properly prepare your skis for summer storage, clean them with a damp cloth, remove rust and burrs with a diamond stone file, and apply a thick coat of wax to ensure that the bases do not dry out. Store skis in a cool, dry place, such as a closet in your house.

To prepare your ski boots for summer storage, take out the liners and dry them thoroughly, buckle the boots loosely, and put the power strap on.

The following video provides a great overview of how to properly store your skis and boots over the long summer season so be sure to give it a watch.
  Some ski techs recommend turning the DIN setting of the bindings all the way down to the minimum (so a 6-14 binding you'd screw down to 6).  The idea is that the binding's springs won't be under tension all summer long and therefore won't weaken the springs over time. When Fall comes, be sure to crank them back to your normal DIN setting before heading out to ski.

Burrs and rust on your ski edges cause drag and slow you down on firm snow so it is important to properly maintain your ski edges so that they perform properly for you all season long. In the following video you'll learn how to inspect your ski's edges, remove burrs, polish rust and wipe the bases clean.