I have found that the more you know about your item and more information you include in your listing, the more likely you are to get a sale. So instead of green silk dress, you need to put the designer name, preferably the style name, the season/collection, etc. Also, make sure that you include photos of the dress on a person. It can be you or a photo pulled form the internet, but I won't buy anything on ebay or poshmark that doesn't include a photo of someone wearing it.