Regardless of where you go or what you will be doing while camping, if  you
are using an RV, it is a good idea to have a checklist to go over before
going on any camping trip.  This list will cover the necessities all too 
often overlooked.

1) Propane tanks.  Are they FULL?  Never go anywhere for an extended period
   of time with half full bottles.  Take the time to top them off.
2) Water storage tanks and water lines.  When was the last time you sanitized
   them?  If you can't remember, its been too long. 
3) Water pressure test.  It is a good idea to do all pressure tests while in
   an area where work can be done and not while camping.  Be sure to
   check the water heater pressure relief valve.  Be sure it doesn't leak. 
   It would also be a good idea to replace the drinking water hose gasket 
   now while you are checking everything out. 
4) Sanitation tanks and removal system.  Be sure your sanitation tank is 
   treated and that all removal hoses and fittings are in good shape ready 
   for use.
5) Tire maintenance.  Make sure all tires (including your spare)are in road 
   worthy shape at proper tire pressure.
6) Electric brakes.  Be sure to test your electric braking system.
7) Wheel hubs.  If your RV has sat for a long period of time, it would be a 
   good idea to remove the cap from your wheel hub and check the condition of
   the grease. If it needs replaced, better to do it now rather than later.
8) Lighting.  Ensure all lights are working including your reverse lights. 
   Always carry replacement lamps for both the interior and exterior.  
9) Electrical system.  Make sure the RVs electrical cord is in good shape.  
   Look for any dry cracking or exposed wiring.  Make sure the electrical 
   plug isn't burned, swollen, or have any loose pins.
10) Air conditioner. Cycle your A/C on and make sure it is in proper working
    condition.  If it begins to hum when you turn it on, it is possible that
    Mud daubers have built nests in your fan blade remove these if necessary.
    If this isn't the case, the start capacitor for the fan motor is 
    probably bad.  
11) Heat test.  Verify your heat is in proper working condition.
12) Ensure your refrigerator is in working order if you intend on using it.
13) Check the stove and oven for proper operation.
14) Battery check.  Charge your battery and take it in to Wal-mart, Autozone 
    or other auto parts store and have a load test done on your cell. Replace
    if necessary.  
15) Check your charging system.  Make sure it is putting out DC power.  This
    not only charges your battery, but also powers up your 12V side of your
    RV.
16) Check leveling jacks for damaged parts.
17) Check water heater.  Remove heater element Make sure it is in good 
    shape.  Replace anode if necessary. Check propane side of water heater. 
    Now would be a good time to drain the water heater to remove sediment 
    that may have found its way into your system.
18) Fire Extinguisher.  Make sure it is in date and where you can find it.

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Checklist

Wheel chalks 
Drinking water hose 
Pressure regulator for water/filter
Tools
Spare fuses & light bulbs
Sewage disposal hoses and connectors
Leveling jacks
Level

Long handled lighter 
Utensils, knives, plates, cups
Hand towels and wash clothes 
Detergent for washing
Crock Pot
Cooking ware 
Camping chairs
Bedding
Portable electric heater (you never know)
Portable fan (you never know)
Clothes
Bathroom items (toothbrushes, soap, shampoo, towels, deodorant)
Trash bags
Storage bags, saran wrap, aluminum foil

Here is a PDF file of the checklist you can open and print.