Keep your signature to the 4 line limit to avoid annoying users who pay for their network access time. Reference the source of a document and provide instructions on how to obtain a copy. Do not forward personal e-mail to mailing lists or Usenet without the original author's permission. Without face to face communications your joke may be viewed as criticism. Some of these will generate replies to your posts to let you know they made it through.
Many users visit the test groups to help out new users.
Try to make it as reader-friendly as possible. Avoid just putting entire messages into one big file. Edit the messages which contain the essential information. Sometimes people will respond but request to remain anonymous. Summaries should honor this request.