Several additional things that need consideration:
- The battery should be fully charged. If not charged fully, the electrolyte may freeze. Don't try charging a frozen battery! If you have any reason to believe it's not fully charged, drive a really long trip (ideally 2 hours), or purchase a charger. Do note that cold batteries require a higher charging voltage, so your charger should be temperature-compensated or have a toggle button for cold conditions.
- The coolant must tolerate -30 degree F temperatures. If you use factory spec mixture, it does, but if you have topped the coolant up with water for any reason, it may not.
- The windshield washer fluid doesn't necessarily withstand the cold. You should top it up with concentrated fluid, if you have any reason to believe the mixture isn't going to withstand the cold.
- The fuel. If you have a diesel vehicle, and you use summer grade fuel, it's not going to start. Even ordinary winter grade fuel may not help in starting, you may need to have really-cold-winter grade fuel. However, I you said "gas" so I assume this doesn't apply to you. (Congratulations for making a good choice! Gasoline vehicles are ideal for cold temperatures!)
- If possible, park the car under some kind of structure with roof. Even if the structure is open and not heated inside, the roof is going to make it less likely that the windshield and other windows will have frost on them (the roof prevents the heat from radiating away to the space). If not possible, purchase some kind of windshield cover or complete cover for the car and use it.
- Operate the windshield washer before parking. This way, if the windows have frost on them after parking in the cold, if you have to scrape the frost off with a scraper, the operation of the windshield washer ensures the windshield will be clean and not have a layer of small sand particles. It's these sand particles on a dirty windshield that make the windshield full of scratches.
- After starting up, drive it easy, don't haul ass. The engine is going to last longer if you let it heat up with gentle driving.
- The suspension components may not like the cold, so don't drive over speed bumps at high speed.
Apart from these, battery charge and heating up to start the engine (and perhaps warm the interiors with an interior heater) will make your life easier, as Cullub and Solar Mike said.
In extreme cases (full windshield washer fluid tank or full diesel tank), you may need to drive the fuel tank nearly empty of diesel and fill up with really-cold-winter grade fuel, or empty the windshield washer container by operating the washer and fill up with the correct mixture.
Off-topic: I currently work in the weather forecasting industry and know well that forecasts can and do change. So, be sure to keep an eye on the forecasts. In the best case, the temperature won't be as cold as forecasted, but in the worst case, it may be even colder!