Yes, I'm a pilot, and we love checklists. But this makes sense. Make a checklist while at home of all the important numbers and contacts and basic factual information you may need on each end of your trip, first among them the confirmation code the airline gave you when you purchased the ticket.
While you may still be able to find your reservation in the electronic kiosks using just your name and a credit card, that confirmation code really is your ticket these days, and it's much smarter to have it instantly available.
List, as well, any options you may need to remember in case something goes haywire with your planned flight schedule -- also known as Plan B. Airline employees who fly on passes are expert at this because they can never be sure whether their first or second flight choices will have empty seats. Having a Plan B and Plan C -- and sometimes even a Plan Z -- can be a real stress saver.
In practical terms, that means if the weather is looking bad on your day of departure and you're leaving after noon or in the evening, consider what you'll do if, for some reason such as a canceled flight, you won't make it to your destination as scheduled. Who needs to be called, what problems will that create, and how can you comfortably plan for them? Having those answers ready lowers the stress level.
Even if the security lines are never a problem at your originating airport, other things can go wrong, and the greatest stress minimizer of all is to be fashionably early and have time for a latte or an overpriced airport snack before boarding time. When you're not yet in sight of the gate, real stress increases in direct inverse proportion to the number of minutes remaining before the flight departs, especially if you suddenly find yourself at the back of a long line anywhere in the process.
Don't guess. Use a bathroom scale or buy a hand scale at your luggage store. If the bag is more than 50 pounds, it will snag a $25 to $50 surcharge with no sympathy from the agent. One trick, however, if you haven't weighed them and think you might be close to the limit, is to head for curbside check-in. The skycap may or may not be a weight-limit Nazi. Don't forget -- you can never curbside check international baggage.