Take advantage of hotel parking packages
This is a really neat life hack that most people don't know. Sometimes, if you book a night at an airport hotel, your reservation gets you free parking and a shuttle to the airport. And sometimes, booking a night at an airport hotel is cheaper than paying for a week of on-site parking. Seriously! You can save a solid $50 at certain airports. It's worth checking out.
This is both an airport parking tip and a good piece of advice for flying in general. Leave early. Expect everything to go wrong. Expect to get lost on the way to the airport. Expect to get a speeding ticket. Expect that all the airport parking is taken. Give yourself plenty of time to get settled and recalibrate your plan if need be.
Thief-proof your car
Most lots have at least minimal 24-hour security. Verify the security situation before you fly and scan online reviews for past patrons that had problems. Remember, you're leaving your car in an unfamiliar place for an extended period of time. Hide your valuables from view (or better yet, take them with you) and triple check that your doors are locked. A stolen GPS can sour even the best vacation.
Keep your parking ticket safe
If your lot dispenses time-marked parking tickets, don't lose your ticket! Otherwise, you could have to pay a lot of money to retrieve your car. Put it somewhere safe within the car itself. Placing the ticket on the dashboard in plain sight will make it easy to remember.
Make note of where you park
You don't want to spend the end of your journey wandering around the airport parking lot in search of your vehicle. Text yourself or a travel companion where the car is parked, and write it down on a piece of paper as well. When you come back from your trip, you won't have to struggle to conjure up the floor number or lot section.