On Cape Cod where it can get into the 20s over the winter. We were gone from November till May last year. Here's what we did
1. All food out of the house, freezer and fridge propped open.
2. AVgas in the mower and power washer. 93 octane unleaded and Lucas stabilizer would be ok as well. The neighbor used the snow blower so I didn't need to worry about that.
3. All batteries out of battery operated stuff (puck lights, remotes, power shades).
4. Unplugged the garage door openers.
5. Put the car batteries on a Battery Minder.
6. Water off, but this was a mistake. I have a forced hot water heating system and the pressure got too low without makeup. I've since learned that this is solved by running a separate line to the furnace that doesn't require the rest of the house to be on. If I were to do this, I'd run the PT valve overflows to a sump somewhere.
7. Heat set at 50°.
8. Got one of these.
http://www.protectedhome.com/homesitter-p-118-l-en.html9. Had the local handyman check the place regularly.
10. Unplugged everything, TVs, cable, internet. Left one inside and one outside light on a timer.
11. Screwed the cooktop vent closed so critters couldn't crawl in there for the winter.