Hire a housekeeper or a cleaning staff to clean and maintain your home once a week to keep it protected from dust and mold build up. Dust can build up fast and can ruin your furniture if it is left for too long.
Make sure you have someone to watch over your place. It is good to ask a neighbor to check on the place every now and then. If you trust them, then give him an extra key.
Set up an alarm system for the long periods you are away. Protect your investment and make sure you have an alarm company that will send out staff or the police if someone tries to break in.
Set up some automatic lights. By setting up your lighting system and making sure it goes on in the evening, you will scare off any potential robbers or criminals.
Make sure the summer home is properly air conditioned. If your place gets moist and overheated during the summer months, it might experience a mold and rust build up.