Source: These guidelines were adapted from those submitted by members of AOLIN (Australian Open Learning In-formation Network), from "The Internet Roadmap," an Internet training course by Patrick Crispen and from The Net: User Guidelines and Netiquette by Arlene Rinaldi.

Posting
Come forward and share your thoughts with the group. Keep your questions and comments relevant to the focus of the discussion group.
Length of Message
If possible, try to restrict a message to a screen; two screen pages are still tolerable. Brevity is a virtue since reading long text on the screen can be tiresome for both the eye and mind.
Writing Style
Use short sentences and simple English. Avoid rambling running prose with complex syntax and a multitude of coordinate and subordinate clauses. Capitalize words only to highlight an important point or distinguish a title or heading. *Asterisks* surrounding a word also can be used to make a stronger point. Capitalizing whole words that are not titles is generally read as SHOUTING and is not acceptable Netiquette.
Spacing
Neat, meaningful spacing can ease mental processing. Try this:
  • Have short paragraphs separated by a blank line rather than long paragraphs with a tab indent for the first line
  • Put questions on separate lines rather than stringing them together in one paragraph. This makes it easier for people to annotate or answer them.
Numbered Items
Ideas and arguments are clearer if presented in point form; if they are numbered as well, it will make cross referencing even easier.
Spontaneous vs Considered Response
While much can be said in praise of spontaneity, if you are dealing with a sensitive or controversial topic, give yourself a little more time to reflect on the arguments and counterarguments, then compose a considered response that you will not regret  afterwards. Remember that electronic documents travel fast, get reproduced easily, and live long in people's files.
Wit and Humor
A small and occasional dose of wit and humor does wonders for a discussion that is beginning to take itself too seriously, and can also break the ice for a discussion with a hesitant start. Too much clowning around and too many flippant jokes or remarks, however, can be irritating and offensive to most people. Be careful when using sarcasm and humor. Without face-to-face communications, your joke may be viewed as criticism.
Etiquette and Protocol
If you want to acknowledge and thank people for their comments on your views, do so privately rather than publicly. Most important, resist the temptation to "flame" (lambaste or criticize antagonistically) others. Remember that online discussions are meant for constructive exchanges. Treat other forum participants as you would want them to treat you. A good rule of thumb is to wait 24 hours before responding to any message you perceive as a flame. You may see it differently later.