5. Hit the power wash
If your trip involves a beach, sandy desert, or salted icy roads, use a power washer now and again to get dirt and other contaminants out from hard to reach areas under the car, like inside the wheel wells, etc. It's the car equivalent of flossing... meaning you never do it but really should and there's no car dentist to guilt you.
6. Know your enemy
Keep an eye out for exceedingly awful vehicles. Gravel trucks are the devil, effectively sandblasting the front of your car for as long as you follow them. If you can't get around, because it's a one-lane highway, try to keep another vehicle/sucker in between to shield as much debris as possible.