1) For six months prior to your departure, make a list of all the bills you receive and make arrangements to have them paid in your absence (leave checks for family or friends to mail; arrange for direct debiting of your account). Don’t forget such sporadically-appearing bills as insurance premiums and property taxes.
2) Phone all your credit card companies and let them know charges to your cards will be appearing from Greece. Otherwise, they’re likely to phone to see if the charges are legitimate, get no answer, and put a hold on your cards. It’s happened to me before, and it’s a nightmare!
3) Get your mail held at the Post Office; suspend your cell phone and gym and other memberships.
4) Give a trusted friend your house and car keys and alarm system remote. Buy timers for lights throughout your home, and set them for a variety of times.
5) Leave your house sitter or a family member with phone numbers for other family members, your plumber and electrician, your insurance agent, etc., etc. Also, draw up your Greek itinerary, as best you can, and leave your travel agent’s number and numbers at the hotels where you’ve made reservations.