"Netiquette" stands for "Internet Etiquette", and refers to practices developed over the years to make the Internet experience pleasant for everyone. Like other forms of etiquette, netiquette is basically courtesy in online communications.

Avoid using all capital letters.
IT LOOKS LIKE YOU'RE SHOUTING! Plus it's difficult to read.

Don't criticise another Member's grammar or spelling. Don't pick on or bully another member.

Do not attack another forum or encourage others to do so - if you have a problem with any thread, report it.

Welcome and help the newbie (a term used for new members who may not understand forums the way you do) and don't presume every newbie is a troll
http://en.wikipedia.org/wiki/Internet_troll

When you talk, the tone of your voice conveys great meaning. To add personality and humour to your messages, use smileys or emoticons.

Keep your written communications to the point. Few people like reading text on a computer screen for too long at a time. To keep messages short, use some abbreviations but avoid full text speak as this can be difficult to read and most don’t understand.

Remember that anything you post is a public comment. You never know who's reading it or who may copy it and spread it around. It could come back to haunt you and be careful how much you give away.
Never post or ask others to post their personal details and information in an open or private forum. If you must pass on such information it is best to do so via eMail.

Stick to the topic when posting a message. Don't post unrelated comments, or worse, advertisements. This practice, known as spamming, will quickly lead to another unpleasant Internet practice flaming

What is flaming? Sometimes you might offend someone unintentionally. Be prepared to receive some angry message. This is called being flamed. If you attack back, you will spark a flame war. To contain the heat, the best response usually is no response at all or a heartfelt apology.

When posting, make sure that the subject line accurately describes what the message is about.

A swear filter is in place to block out naughty words, don't purposely swear using methods to get around this.

If you don't enjoy the topic of the thread, close it and open another or start your own but don't leave a rude post.

Remember these are human beings with feelings and emotions communicating together. Think before you post.!