In journalism, cub reporters are taught to answer the 5W's and an H:

Who, What, When Where, Why and How.  It works for me.

  •  Who is the audience?  Who am I to them?

  •  What's the setting?  What's the topic?  What's their expectation? 

  •  When is the program?  When should I arrive?  When must I finish?

  •  Where is it?  Where will I take them?

  •  Why have they asked me?  Why have I accepted?

  •  How am I going to satisfy their expectations?

Every effective speaker I know has a program defining process.  Many use a checklist to insure they have covered the essentials.  Mine is a form which prompts me to identify all I need to prepare.

For me, the essential is knowing: knowing the audience, knowing what they want me to achieve before, during and after, knowing when I am to finish and knowing where the nearest exit is in case I need to escape.