Photos
Photos of your car will seal the deal. Make sure you abide by these time-tested rules of c/l sellers:
Make sure 1/5th or less of the car is in frame at any time. Let the buyer's imagination assemble the full picture, hopefully without all the body damage you're trying to hide.
You really want to capture the setting, so if you must take a picture of the whole car at once, take it from eight or nine miles away
Remember: potential buyers will want to know what the car looks like at night, so that the perfect time to take pictures!
Never clean out the interior of your car. Clothes and trash strewn everywhere are signs of responsible automobile ownership.
If you took pictures of your now used car when it was new, post those instead of anything approaching the present reality. Extra points if a clearly visible time stamp from four years ago is burned into the picture.