attention to the garage door track, especially during the summer and fall when there might be grass clipping or leaves being blown around by the wind. keep the tracks clear of any debris and your door will be able to open and shut smoothly and without resistance.
as for the door itself, you should also get into the habit of giving it a wash every once in a while. you don't need any special chemicals, just plain old soap and water will do. wash the exterior of the door to keep it looking great. while you're at it, you can closely inspect the door for any potential warning signs of wood 