Read Chapter 4.3: Good Writing in Business Communication for Success. You can omit the last section, headed 'Rhetorical elements and cognate strategies', if you wish.
This reading identifies message fidelity as the central goal of good business writing. Fidelity means accurate communication of your intended message, with a minimum of noise that may trigger breakdown or misinterpretation. For mainstream Western business audiences, effective written communication follows language rules, is easy to read, attracts the reader, meets reader expectations, and is clear, concise, and efficient. When you are clear on your writing purpose and learn as much as you can about your audience, your business messages will be more effective, and may sometimes reconcile multiple goals.