set it up perfectly and take lots of shots.
This!
There's nothing worse than see ads with the camper half arsed setup on the too small front lawn with the wife half in a photo holding up the tent or awning because their too lazy to actually set it up properly.
Last year we looked at a few 2nd hand campers for both ourselves and friends and I noticed the following on a lot.
The below is in no way directed at you kalex, but observations about others for sale.
Poorly setup in photos and then sellers being reluctant to set it up so you can have a proper look, one guy wouldn't even get it out of the carport! If you don't have the room be prepared to take it somewhere and set it up for a prospective buyer.
Understand what you are selling. If you don't know what it is fitted with find out off the manufacturer. Just because it has white sunraysia's and an axle flip, it doesn't mean it has 'fully off road HD suspension' as one seller put it. Turns out it was a 40mm axle on slipper springs!
Scrub, scrub, scrub. There is nothing worse than a putrid camper, I know its a quality Aussie made tent and trailer that can handle all conditions, but I don't need the red dust as proof. Wash the canvas and scrub the trailer, if the paint is bad give it a fresh coat, but not a half arsed job like one bloke did to his rear fold camper. Tried painting the rims and trailer with cheap pressure packs, but mainly got the tyres and canvas.
Some accessories are good, but don't try and offload all of your old camping junk, most buyers are already tent campers and thowing in your 6 year old 'used' porta-pottie is not a good selling point to most people.
Be realistic on price. Allot of brand name campers we looked at people were trying to get 80% of the new purchase price on a 10 year old camper. Unfortunately (good for some) there are more campers on the market than there is buyers.