At the airport lot, back your car into its spot. If you return home to a dead battery or any other problem, this will make easier access to the battery or to a tow truck.
Many airports now offer less expensive parking lots but it takes time to get from them to the airport. Leave yourself enough time for that shuttle bus.
Pack anything that will be hard to replace in your carry-on, like those special running shoes. Of course your medications and important papers go into your carry-on. Put your quart-sized plastic bag with your liquids in an outside pocket or other easily accessible place.
Have complete information for your hotel in case of a delay, including phone number, fax number and email address. Have a printout of the hotel's location, for your own use or to show a cab driver.
If you are a frequent flyer member, save your boarding pass. If the airline goofs you don't get credit for your flight miles, your boarding pass is the proof you can provide that you took the flight.
Make your checked suitcase stand out from the rest. We use neon green luggage straps and can spot them as they come down the luggage belt and even have seen them being loaded onto the plane. No one is going to walk away with our bags by mistake.