Preventive maintenance is a must. Besides, a well maintained vehicle is more enjoyable to drive, will last longer, and could command a higher resale price. First things first. Read your owner's manual and follow the manufacturer's recommended service schedules.
Cold weather makes existing problems worse.
Note that a gas tank which is kept filled helps keep moisture from forming. The cooling system should be completely flushed and refilled about every 24 months. The level, condition, and concentration of the coolant should be checked periodically. The tightness and condition of drive belts, clamps, and hoses should be checked by a pro. Carry an ice-scraper.