Set your text in a serif type font. That's the font with the little feet like New Times Roman or Garamond. On the printed page, it's easier to read.

Don't double space between paragraphs. This tells the reader to stop reading. Instead, single space and indent the first line of each paragraph.

Don't justify the copy. I know some business writing people like it because it makes the paragraphs square, but it makes the text much harder to read by creating odd spaces in the text.

Try to get rid of widows and orphans. A widow is line that only has one word or part of a word; an orphan is line that flows to the next column or page all by itself.

Try to avoid hyphens. Too many hyphens break up the flow of the text and make it harder to read.