DrDoc - 5:53 pm on Jul 12, 2007 (gmt 0)

Font choice is one of the most important aspects.

Things to do:
choose a serif font
use a slightly expanded line height
use first-line indents for all paragraphs
mix blocks of text with bulleted lists where appropriate
indent and italicize block quotations

Things NOT to do:
never justify the paragraphs
never use large blocks of text or several paragraphs without breaking it up with an image insert or similar
never reduce margins below 1.25", or else people will start covering up parts of the text with their thumbs