Disconnect outdoor water hoses
Faucets that are not freeze proof need to be covered or insulated to protect them from sub-freezing temperatures. Be sure that freeze proof faucets are drained dry once the valve is shut off. Any trapped water in an exposed faucet spells trouble, even if the faucet is labeled as freeze proof.
If you have a well
If your water is supplied by a well, take precautions to keep the pump and tank from freezing. The tank and pump should be covered. In cases of prolonged cold weather, place a light bulb in the pump house. Assuming that all the holes and cracks in the pump house are sealed, the warmth from the light will usually prevent freezing.
Seal holes and cracks in older homes
Homes that were constructed fairly recently are usually insulated enough to prevent water pipes from freezing. In older homes, seal holes and cracks in the foundation with caulk or insulation. Consider letting a faucet or two drip if the pipes will be exposed to below freezing temperatures for more than a few hours.
Don't forget livestock and pet water sources. If they drink out of a container, it will also freeze when temperatures are below freezing for just a few hours. Electric and solar water-heating devices are available to prevent your pet's water from freezing. Most people don't see the need for these tools until Rover's water bowl turns into an ice tray. If you find yourself in that situation, provide fresh water to your animals a couple of times per day.