In my work, I usually think about four things when I begin to develop a communication plan within an overall change management program:
#1: The Receiver - who has to get the message and what you want them to know, feel or do when the message is delivered.
#2: The Type of Message - strategic, tactical, urgent, informational, inspirational.
#3: The Sender - Executive/Senior Leaders = Strategic/Company/Inspirational messages. Manager = Tactical/Urgent Action/Inspirational messages. Respective Function = Informational.
#4: Company Culture