Remember that a big, big battery and correct engine oil are doubly important with the diesel. As the temperature drops, the fuel gets thicker until finally it can t flow through the fuel lines. You can buy it premixed during the winter in areas where it is consistently cold. In the Puget Sound area, where we all know it never gets cold, none of the diesel is winterized. Gasoline is probably the best way to thin diesel, but is harder on the engine and can even be dangerous if mixed at too high a concentration.
Alcohol is also somewhat hard on the engine, but is safer.
If obtainable, kerosene is the best choice, since it is the closest to diesel fuel in flash point and lubricating qualities. It is also less critical if the mix is a little off and it will affect mileage only slightly. Kerosene is harder to find, but goes a long way. The first rule of rain and snow driving is to have a good tread. With that, you will stop and start quicker and dramatically reduce hydroplaning.