I use my Coach all the time in the winter. Not knowing what kind of RV you have more specific info will be limited.
You can purchase heating pads to place on all your tanks..black, gray, & fresh. I also have a heater in my water compartment where all the valves are. A drop light will keep that bay warm enough to keep your water pump from freezing. Keep your heat on inside your RV. Keep your doors open to your sinks if it is really cold. Any exposed pipes will need to be insulated. The heating pads, or extra heaters in the bays will draw quite a bit of power. So make sure you have plenty of fuel for your generator to charge the batteries back up, unless you have electrical hook ups.
Your sewer hose will need to be emptied right after you dump your tanks. Do not leave it out to freeze up. Empty the tanks, empty the hose and put it away. Same goes for your water inlet hose.
There are heater tape options that you can use to wrap your pipes. There are some on the market that do not use a lot of power. Heater tape, heaters, heat pads, can run your batteries down quickly. Especially when your running your furnace. Keep your batteries maintained and up to snuff. Any weakness will be readily seen when it gets cold.