1.) Address the question. 2.) Attempt to be fair and unbiased. 3.) Give the most accurate information you can. 4.) If you don't know the answer, feel free to seize your opportunity to shut up. 5.) Not everyone will like your answer or agree. It isn't that big of a deal.

Well, AntigoneRising pretty much nailed it but I wish to add a few more more to her list: 6) Remember something called "manners". There is no reason to be rude, whether or not you agree or disagree with the asker. If you choose to insult, do not expect anyone to actually read what you are SAYING. Insulting is a good way to make the reader's minds shut off and just makes YOU look like a fool. 7) Try to make it as legibly written as possible. The better your grammar and spelling, the more readers are going to be able to read your post. A few misspellings or grammatical errors are not bothersome but when the whole thing is one misspelling and/or grammatical error, it is hard to read. Also, atrocious spelling and grammar, or chatspeak, is not condusive to a serious sounding post. 8) If your mind heats and you are going to head into a flame war, do something else for an hour to cool your head, then come back to the question (I recently did not follow my own advice in this one). 9) If you are trying to prove something, supply reputable sources for your statement. If you do not have them, your opinion is going to be just that... your opinion. Do not expect it to be taken as more than that. 10) You do not have the copyright on the Truth. Another person might interpret your sources differently. Accept this.