No counter-quoting
Counter-quoting is when you respond to every sentance in the other person's post systematically. The other person, in general, does the same. It looks like this;
---------------
Person B's post
Person A
Person A's argument No. 1
Counter argument to person A's argument No. 1
Person A
Person A's argument No. 2
Counter argument to person A's argument No. 2
Person A
Person A's argument No. 3
Counter argument to person A's argument No. 3
Person A
Person A's argument No. 4
Counter argument to person A's argument No. 4
Person A's post
Person B
Counter argument to person A's argument No. 1
Counter argument to person B's counter-argument No. 1
Person B
Counter argument to person A's argument No. 2
Counter argument to person B's counter-argument No. 2
Person B
Counter argument to person A's argument No. 3
Counter argument to person B's counter-argument No. 3
Person B
Counter argument to person A's argument No. 4
Counter argument to person B's counterargument No. 4
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As you can see, it takes up a lot of space, looks ugly, and isn't very informative. In short, it isn't much more than a flame war. Whilst it's important to lay out posts in a ordered manner to make them easier to read, this isn't the right way to do it.
No halls of mirrors
This is the habit of quoting other people's quotes. It looks like this;
---------------
Some guy
Some other guy
Yet another guy
Some guy
Yet another guy
Counter argument to second post
Counter argument to third post
Counter argument to fourth post
Counter argument to fifth post
Counter argument to sixth post
---------------
Whilst quotes within quotes sometimes have their place, it frequently gets ridiculous. Halls of mirrors take up way too much space, and are totally unnecessary. Remember that in order for a hall of mirrors to build up, it means that every person before you already posted the same thing you did, minus your post. That means that the same few posts can get repeated up to fifteen times on every page!
If someone wanted to see who you were replying to, all they need to do is to scroll back and read what the other person wrote. Save quotes for long discussions, when you are responding to a specific point that someone made more than one page ago.
No name-calling
It's tempting to call someone else stupid. Don't do it; the other person will never believe you.
General guidelines
Keep your posts concise. That means, keep them as short as possible, without leaving out any important details. The best example of this is a concise dictionary; words are defined with the shortest possible explanations.
Write in paragraphs, a few lines long, and remember to leaves spaces between paragraphs. Keep each paragraph to a particular point. Paragraphs are easier to read and digest.
Remember the rules of spelling and grammar. Though there is 'right and wrong' in language, the rules of spelling and grammar do make it easier to communicate your ideas. Additionally, if you don't spell things properly, people will think you're an idiot and they won't believe anything you say.
Keep it simple. Write in a way other people are going to understand. On the whole, Gaians aren't very smart. They might not know the meaning of the words that you are using, especially words to do with science and philosophy. Remember, even if you are responding to one person, anyone on Gaia might want to read your post.