When selling your forum signature try and be as descriptive as possible! Include all the information you possibly can as every little detail will help the buyer decide if your signature meets their needs. Include information such as,

• Forum name
• Posts
• Posts per day if possible
• User name
• Custom forum title
•  How long you have been a member
• A direct link to the specific forum
• Mention the exact spot their add will be placed
• Give detailed information such as, is the signature allowed color, how many characters, and any other important information you can include regarding the positioning and look of the forum signature for sale.
• Provide information pertaining to what type of forums you post in on a regular basis. (be specific) Example: Web Master Forums is a general term, mention specific forums at this Web Master Forum such as html web design, SEO and Marketing, and more.

Remember that information is your key to selling your forum signature so the more info the better your chances become.