I would leave in an environment that won`t change to much during the seasons. No cellar or attic that isn`t isolated or heated, but a cottage in the middle of the house where it usually is a constant temperature.
I would leave strings in tune, maybe loosen them a little, but still enough to keep the neck in tension. Oil the neck a couple of times, maybe add a conditioner on top, clean the body and remove the battery in case it could corrode or leak batteryfluid.