The morning you are to break camp, turn off the water heater early so that it will have some time to cool.
Don't forget to switch the refer over to 12V.
Turn off the gas.
Lower the TV antenna.
Walk around before closing anything. I have learned to drag my feet so that the obvious will become obvious, power cable, water hose, sewer pipe.
If you are to dump at a dump station, don't forget to open the valve on the toilet.
I agree with Chris on stocking and the checklist. I once forgot the pillows

:'(
My checklist is on a spreadsheet so that it will calculate how much of things I will need for the whole trip by entering the number of days I am to camp.
Learn to back up the TM before you need to back it up. Mack's first and third suggestion come to mind here.
Buy some stick on levels. Set the TM up at home and level via the refer. Close the TM and latch. Apply stick on levels. Now when you level at your camp site you can get it right before you open anything.
If you have the scissors stabilizing jacks, use a cordless drill with an allen wrench to do the cranking for you.
If you are not used to it, you will quickly learn to conserve water. If you act like you are at home, chances are you will use up your fresh water and fill up your gray tank in the first day.
If you are opening and/or closing and something doesn't look or feel right, investigate before you break or bend something.
Close the side wall curtains before folding, they will stay cleaner.
If you have any questions, don't hesitate to ask. The folks here have learned alot and are great about sharing.
Most of all, ENJOY.