How to Use Proper Forum Etiquette | eHow.com
Read the forum rules. Even if you're excited to be a member of a new forum and can't wait to join in, take the time to find the group policy page and read it thoroughly. Some forums are fussier than others about Internet etiquette.
Lurk a little before you dive right in. Read a number of posts, or check out the group's archives. Get a feel for the tone of the forum so you can participate accordingly.
Remember your face doesn't show. Words alone can convey sentiment, but without benefit of inflection or facial expression, they can be misconstrued. Use descriptive wording, emoticons or .gifs to ensure your meaning is clear. By the same token, don't jump to conclusions about another person's intent in posting an unclear comment. When in doubt, ask for clarification.
Type in lowercase or standard case, not in all caps. By the rules of netiquette, all caps equates to shouting. If you type with all caps, you will annoy and possibly offend other forum members.
Say online exactly what you would say in person. In other words, if you wouldn't say it to the person's face in front of your Grandmother, you shouldn't type it into a forum.
Be respectful. Internet etiquette is similar to standard etiquette in this area. Appreciate that your opinion is one of many. You can disagree with another person without being disrespectful or rude online.
Ignore Trolls. Netiquette guidelines are very specific where they're concerned. If you engage in conversation, you'll raise your blood pressure and empower the Troll. You can't win a flame war, and you can't sway a Troll's opinion. Often, they don't even care about the subject; they live for the conflict and nothing more. Trolls are common and not worthy of your time. Ignore their posts—no matter how inflammatory—and eventually they'll get bored and move on.