Remember once it is out there you cannot get it back. Be sure to observe before participating when you first connect with the Internet. Find out the rules and be polite when asking questions. Before posting to a discussion group, bulleting board or chat room spend some time learning the atmosphere and style of the area before launching in. Read these first so you won't be asking a question that has been asked and answered a thousand times before.
Some service providers have rules against sending commercial-type messages.
Do not pass along warnings about Internet viruses or any other threat without first checking with the Virus Hoaxes and NetLore page or Symantec Corporation Virus Hoaxes page . This is a common trap for Internet beginners. Try to be the smart one who knows how to end the hoax instead of perpetuating it. Some of these programs are known to have damaging elements embedded in them and you would be responsible for distributing it. Use the same courtesy as you would extend to someone you were having a phone conversation with but realize that no one can hear your tone of voice.