The best way to stop your pipes from freezing is to have a plumber professionally install pipe insulation. This will prevent pipe freezes at almost any temperature.
You can also increase the airflow to your pipes by opening up cabinets and doors while the heat is running. This helps expose the pipe to warm air and increases its temperature.
Finally, always leave your taps dripping when the temperatures fall below freezing. Moving water is less likely to freeze, as it does not stay in contact with the cold pipe for as long.