Start with the only thing between you and the roadway: your tires. Inflation comes first, then damage, obvious punctures and excessive wear. Bring the tires to the proper pressure and if they're 30 percent lower than the recommended psi you probably have justified your vehicle check and need to seek assistance. The damage you're looking for is reflected in bulges or gouges in the sidewall this may also require a professional opinion. Next check for objects that have punctured the tire like nails, screws or glass and finally check for excessive wear. Consider the wear bar (a raised bit of rubber between the cleats of the tire tread) if any of the tire's wear has reached the wear bar you should consider replacing the tire. Remember to check the entire tread surface, not just the outside, turn the steering wheel to position the tire if need be.
Other overlooked maintenance tips for vehicles involve sight and sound. Start with the windshield wipers, they should be checked for fraying and erratic movement. Turn the wipers on and spray washer fluid on the glass and be aware of any knocking noises that might signify a bad wiper motor or a loose bolt holding the wiper arm to the wiper transmission. Now move to the lights and mirrors, obviously they should be illuminating and clear of any obstructions. Be sure to include the rear view mirror, which may mean that you might have to shift your load.
Next raise the hood of the car and be prepared to get your hands dirty and challenge your sense of hearing. Listen for unusual noises and if you want to add some levity to this drill consult the Car Talk guys' sound emporium at cartalk.com and try to identify the errant whirr or clunk.
Next do a fluid check. Start with the motor oil and don't quit till you've checked the brake, power steering, and transmission fluids. Any extreme low levels should be followed up by a prolonged glance at the pavement for leaks.
Finally, don't let a commonly overlooked maintenance car tip ruin your trip. Consider any dash lights that are lit as a nudge to your shoulder telling you to get it checked out. This trip may be the time that whatever is causing that check engine light to come on will move to the next level.