Avoid excessive punctuation, especially exclamation marks.
Rule sparingly, consistently and keep rules plain.
Horizontal rules are a psychological barrier.
Too many will discourage the reader from scrolling.
Be polite, be honest.
Phrase statements in the positive.
Expand technical terms and informal contractions to become authoritative or formal.
Rhetorical questions may discourage the reader.
Your message is a monologue.
Use the double quote symbol consistently before and after a phrase.
Learn how to use the apostrophe.
A named group of people is an object and should be refered to as "it", and not "they".
Do not use dotted lines in EMail forms.
Text may be printed to paper as small as 10 lines per inch.
Allow a minimum of three lines height for printed forms, signatures, etc.
For EMail, always format to 72 columns or less.
This allows an EMail to be quoted four to eight times before word wrapping breaks the lines.
After writing your text, run a simple text editor, such as SimpleText, Pico or DevPac2.
You may need to set a fixed width font, such a Courier. To obtain a 72 column rule:
Type: 0123456789
Cut and paste it seven times, then type: 01
You have now marked 72 columns.
Resize the text editor window to this edge.
Anything beyond this edge requires reformatting.
Highlight an entire document to locate spurious, trailing spaces.
Do not use tabs in EMail, users' tab settings may be set to five or eight spaces.
For desired results, replace all tabs with spaces.
Spiky bullet points may confuse Asian readers.
For HTML, use default the bullets.
For EMail use a lower case "o" followed by two or more spaces.
Be especially consistant with bullets.
Avoid repetition in your content.
Check your spelling.
Consider separate regional versions, for example UK and US versions.
Failure to do so may have a negative effect.
Get someone else to proof read your work and listen to their suggestions.