The Internet itself has grown from the grassroots up. And with it, the concept of Netiquette has evolved. You'll learn netiquette as you go. Here are some main points, most having to do with e-mail and other written material you send out, but some, too, having to do with making your own Web page.
People regularly communicating by e-mail expect prompt replies.
It's better to err on the side of under-capitalizing when using the Internet. Realize that no one can hear your tone of voice or see your gestures. Take care that your written communication accurately conveys what you mean and how you mean and how you mean it. Never, ever forge messages in some one else's name. It's just good advertising for them.