*Include detailed dimensions
*Add clear, well lit, pictures. Most people won't bother to look at a post if it doesn't have them. Try to take pictures in natural light and, if there is damage, include a photo. It's better to add a picture of your item (rather than a picture from a company website) because buyers want to see the piece they're getting--not what a new one would look like.
*Be sure to list the best way to get in touch (most people prefer email) and the times you are available to show/sell the items posted. Respond quickly to inquiries--no posting and then leaving town for a week.
*If you're selling a branded/designer item (something that normally sells at a premium), include a picture of the company stamp or mark showing it's authentic.
*You will get some ridiculous offers (I sure did). Try to keep your sense of humor. Be willing to take a little less money if you come across a decent, fair-minded, non-flake. You can't put a price on sanity or safety.