What are seven things you must do in both oral and written messages?
You need to have a good idea of what the message is that you are trying to send, have a knowledge of your audience, and communicate in ways that are clear and understandable for that audience. The other factors are probably subcategories of these.
http://www.members.cox.net/dagershaw/lol/MessageAcross.html
http://www.members.cox.net/dagershaw/lol/communicationDepths.html
http://www.members.cox.net/dagershaw/lol/CommunicationGenderBias.html
I hope this helps. Thanks for asking.