Here are some tips:
~ Describe the car accurately. Make sure you tell the buyers everything you can about it. Leaks, dents and rust should all be disclosed.
~ Take a picture or several pictures. Adds with pictures are much more likely to get inquiries.
~ Ask a reasonable price. Ask too much and it just will not sell. Check ebay motors to see what comparable cars are selling for.
~ Clean, detail and fix up the car. Get rid of any reason people might use to beat you up on the price.