Put the lights and radios that you want to stay powered on timers and plug-in outlet surge protectors. Have extra filters next to the furnace so your friend can change the filter if he or she thinks it's necessary. The day you leave This is the critical period of the dry-dock procedure. Give yourself a couple of extra hours. You do not want to be rushed or forget anything.
All perishable food has to be out of the house.
All electrical equipment you don't need running should be unplugged. Tune in a talk radio station on the plugged- in radios. That may mean turning the humidistat down to zero percent humidity. If no water comes into the house, no pipes can burst or fittings give way and flood the house. You do not even want the pilot light burning while you are away.