Business writing can be creative, but it has work to do, and we should give attention to those who have studied it. One of those researchers is Siegfried Vogele, a direct marketing guru, who taught at the University of Munich and the University of Economics in Vienna. He created the "dialog method" of writing direct mail.
Vogele conducted exhaustive studies of eye movements and discovered a number of rules for effective writing. Among them is the need to use short words and sentences.
So valued is his out-of-print Handbook of Direct Mail that someone is offering a used copy on Amazon for $1,223.86! From that book, here is some guidance that should be work in any setting, direct mail or not.
1. Maximum 15 words per sentence. Put in a full stop after 15 words. It is too late to use a comma.
2. Maximum 30 syllables per sentence is a further limiting factor. Fifteen words and 30 syllables indicates an average use of two-syllable words. This shows you how many single-syllable words you can use if you want to use an essential four- or five-syllable word. In other words, if you use several multi-syllable words in a sentence the maximum sentence length (of 30 syllables) is often achieved with only eight to 10 words.
3. An average of 10 to 12 words in a sentence. The so-called "asthmatic sentences," the half-sentences with one to three words in them, can be used only as bridging elements between the other sentences; otherwise they would break up the "personal dialog." An example of an asthmatic sentence: "XYZ is valid at all times. Yesterday. Today. Tomorrow."
4. Only one idea per sentence.
5. Fewer subordinate clauses and more complete main sentences help the reader understand the text more quickly. Dashes make comprehension more difficult. Commas are suitable only when used with repetition and enumeration; they are not suitable for separating subordinate clauses, which attach secondary ideas to main thoughts.
These guidelines are based on a readability index and are designed to help the reader understand sentences quickly. Hemingway would approve.