Here's what I see that is causing people problems.
1. Way too much stuff - I know they are charging for bags. So travel light. The more stuff you try to take on the plane the more you will mess up in security.
2. Toiletries - Don't even try to skirt the rules. They will get you every time. Use a plastic bag and don't go over the bottle volume limit.
3. Things in pockets - Just empty your pockets into your back pack. It's easier and you most likely won't forget whatever it is you forgot in your pocket.
4. Pissed off travelers - It seems to me the more pissed off you are when you are traveling the more likely you will do something stupid in the TSA line and get secondary inspection. Remember the service industry is just plain hard. They are trying but they are not always the best. Relax and give people a break. You won't be pissed off and you won't forget that you had that second cell phone in your pocket.
5. Don't talk back - If they ask you to secondary inspection go peacefully. The best line I heard out of a traveler - "Ok, This is how it's going to work" - Yeah right, say that in TSA and you may never get on the plane.
I think the important thing to remember is travel changed on September 11th. Yes, the airlines are there to serve you the paying customer but not at all costs. You as the traveler have the responsibility to know the rules, have patience and above all keep calm. And for gosh sakes smile and say thanks as often as you can. It goes a long way.
It's a good life....