Anticipate what you need to do and move quickly
You know when you are in a rush and you're waiting in the security line and the people in front of you can't seem to understand that they must remove their laptops from their bags and empty everything out of their pockets (because this is nearly rocket science)? Don't be one of those people. Understand the proper protocol and move expeditiously. Take off your shoes, remove your belt, and keep the line moving. Having some simple wherewithal can help create a more pleasant experience for everyone.
Don't get angry (or at least learn to hide it)
I was on a late flight that got delayed once. And delayed again. And delayed AGAIN. Frustrating? Sure. Worth going up to the woman at the desk and yelling at her that this is a major inconvenience? Absolutely not. Yes, I really did witness this happen and it's not ok. While it can be trying to encounter roadblocks, you shouldn't place your anger on someone when nothing is going to come of it. Take a deep breath, grab a snack, and find something to occupy yourself.
Respect the environment you're in
For example, I was on a red eye flight (the same one that was delayed three times so everyone was totally exhausted at this point) and a woman was coming on to the plane while talking on her cell phone. She saw that she was seated next to a child and sighed loudly and said to whoever she was on the phone with "Ugh and to top it all off I'm sitting next to a kid!" The father of the child, who was on an aisle seat one row up, asked if she would like to switch. This is probably the worst thing that could have happened for our plane. She plopped herself down and proceeded to talk with the two women next to her (why they decided to indulge in conversation at this time of night on a plane full of people trying to sleep, I will never understand). Not only was she talking to them, she was talking so loudly I could hear her through my noise canceling headphones! Her row was the only one on the flight that left their lights on and created such a ruckus in an otherwise silent atmosphere. She also took a few shots, so I'm guessing she was already tipsy when she got on to the plane; definitely would not recommend.
The moral of this story is that you have to understand where you are and act accordingly. While she was still a little too much for any trip, it would have been slightly better to talk at that volume during an afternoon flight. By taking a moment to think about the other people around you, and decide what would put them the most at ease, you can effectively navigate your travels.
What are your pet peeves in airports? Do you have any rules of thumb to share?