Stay on topic.
Bloggers enable comments on specific blog posts to hear more about the content of the post. Don't change the subject. There's nothing more annoying than seeing a comment on a post about Hurricane Katrina that reads, "By the way, do you know anything about turtles?"
Contribute new information to the discussion.
Twelve people saying the same exact thing in one comment thread is useless and irritating. Before you comment, read the entire thread and make sure your comment offers something new to the conversation. If you don't have the time or patience to read an entire thread, then don't comment at all. The longer a comment thread the more likely someone has already said what you're thinking, and the less likely it is to be read by future visitors anyway.
Don't comment for the sake of commenting.
Commenters who only say "First!" or "Nice site" on an open thread have no business hitting that "Post" button at all. Further, only spammers comment for the sake of adding their name and URL to a web page. Useless comments will gain you the reputation for being a useless commenter.
Know when to comment and when to e-mail.
A weblog comment is a public one-to-many communication within the context of a blog post. An e-mail is a private interaction. A weblog comment that reads, "Oh yeah, that link is cool. By the way, how's your sister?" doesn't contribute to the public conversation and belongs in an e-mail message to the author instead.
Remember that nobody likes a know-it-all.
The best kind of comments come from thoughtful, knowledgeable people who add more information about a topic. However, tongue-lashings from condescending smartypants will go over as well on someone's blog as they would in that someone's living room. Expect to get shown the door in the form of the delete button. When fact-checking, pointing out a typo or dead link or asserting a dissenting opinion, do it in a respectful, friendly way.
Make the tone of your message clear.
No one can hear the tone of your voice or see your facial expression online. Sarcasm, in-jokes and exaggerations can easily be taken the wrong way in a public forum. Remember that a simple colon and a parentheses can change the meaning of a sentence entirely. Use emoticons or additional information to communicate the spirit of your message.
Own your comment.
Anonymous commenting, while sometimes necessary, can be seen as cowardly. Build your identity and own your words by placing your name and weblog address on your comments wherever possible.
Be succinct.
Longwinded lectures are for college professors, not blog comments. Stay short and to the point. Everyone appreciates brevity.
Cite your sources with links or inline quoting.
To comment on specific bits of a blog post, copy and paste the lines in question and add your response below each section. If you're referencing information located elsewhere, provide a short summary and a link to your source so others can click through for more information at their discretion.
Be courteous.
Chances are something someone says in a comment or post is going to irk you. Still, personal attacks are unacceptable, useless and can quickly degrade a discussion to a third grade "Yo Mama" flamefest. Resist the urge, and be respectful and objective at all times.
Don't post when you're angry, upset, drunk or emotional.
There's no taking back a published blog comment - once you post, it's there for everyone to see and for Google to cache. Remember, you're not going to show your best face in the heat of an emotional moment. If you find yourself angrily typing a message into someone's blog comment box - STOP. Get up. Take a breath. Walk around. Give it a day. Revisit the thread when your head is clear. This goes doubly for public blog comments as it does for private e-mail messages.
Do not feed or tease the trolls.
No matter how many articles like this get written, there will always be people who surf around the Internet and inject pointless vindictiveness into any available textarea. Don't let the terrorists win. Do NOT acknowledge these people with refutations, disagreements or even a mention of their screen name."
