Layla has flown once and I agree to keep it as SIMPLE as possible.
We took her for a very long walk the morning of. I know Layla's poop schedule so after her morning poop I gave her a plate of food (knowing she wouldn't poop again until after supper). And she can hold her pee like a champ!
At the airport we went right through security. Your best bet is to keep her in her carrier while you take off your shoes and what not and get everything you need in your bins- except keep a treat in your pocket- you might need this! Put her bag through the x ray as well
Keep her leash and harness on her. You will walk through the metal detector and then they might have to do an additonal screening on your hands because you were not able to go through the explosive testing thing.
Once your things come out of the x-ray use the treat you have in your pocket and put it in her bag to get her to go back in. She might be too interested in what is going on around and all of the "oos" and "ahhhs" to want to get back in. Once she is in, then deal with your things.
Check out this GREAT website!
Dog Jaunt : Taking your dog on a plane : Traveling with a small dog
As for the actual plane ride- I was the one who was a mess so worried about her. But because of her long walk- she was so tired. Just keep in mind, sometimes it is VERY cold on airplane floors- bring a blanket with you to wrap around her carrier in case you need to. Remember she is your carry on and you are only allowed a purse- so I brought a large purse
During the flight I would check on her (she was not allowed up from under the seat) and twice I gave her a treat- during one of those times she tried to get out of the bag so then I stopped giving her treats
she was just sleeping the whole time so she was really fine!