The most common issue is broken hydrants on the outside of the house. Often this is caused by leaving the hose hooked up to the faucet. The water in the hose and hydrant freeze causing a leak in the copper or brass of the hydrant. This also occurs when a dripping hydrant is capped during the summer and left for the winter.
The second most common problem I see is pipes freezing in unheated rooms. The majority of these are laundry rooms that have been added to a house or an inclosed porch where the washer and dryer have been relocated to. There is no way to let the washer hot/cold lines drip overnight like a kitchen sink so they freeze much easier.
Solutions: Take the hoses off the hydrants as soon as you stop watering the flowers. Have any leaky hydrants fixed before winter. Install a small heater in any unheated room that has plumbing. This can be a small electric heater used by many in there office, the temp does not need to be comfortable to you just above 32 F. Insulate any visible water pipe, foam insulation for pipe is cheap and easy to install, they also make Styrofoam hydrant covers.