Monique Rissen-Harrisberg, chief executive officer of voice and communication skills training company The Voice Clinic, outlines some key questions to ask yourself in preparing to communicate effectively and concisely (as quoted on this South Africa jobs website).
What is your objective? Do you want to make more sales, reduce employee turnover, get members to renew? Be specific about your objectives.
What response is necessary from readers or listeners? Do you want recipients of your communication to act or think differently? Do you want to reinforce existing thinking or behavior?
Why would they respond to your message? 
It's all very well for you to have objectives, but you'll also have to offer something that provides value in their terms.
What message content will motivate them to act? What subjects will provide that value to them?
How will you present that content? You can entertain, inform, consult, challenge, solve problems, and more.
How often will you have to repeat the message?
If you quantified your objectives, would the value of meeting the objective exceed the cost of communicating?
