How do you structure a presentation?  The short answer is, logically.  And clearly.  Have pity on your audiences — make it easy for them.  They want a clear, straightforward journey.  Don’t wander through the thickets of your own expertise; give the audience the simplicity of boiled-down expertise.

That said, there are a couple of structures that work better than others.  The classic organization, and one that’s been around since the Ancient Greeks, is the problem-solution format.  Here, you begin with a problem (The economy is heading south!) and then propose a solution (tax breaks for everyone!)

This structure works best when you have a clear issue that you want to address the audience about — and a clear point of view that becomes the solution.

A second format that also can work well is the timeline.  This organization is best when, sensibly, there’s a clear history or sequence of events involved in the information you want to impart.  ("My involvement with the CIA began in 1953 when I was born.  I was the first spy-baby.")  Beware the "and then and then and then" danger of just saying one thing after another. 

A third format is the elimination of options.  This one works best when there are a number of possibilities for the issue you’re discussing, and you want to go through each one in order to show why yours is best.  ("You could increase the number of troops.  But that would put a strain on Army families.  You could…..") 

Each of these formats can work well in a speech.  In persuasive speaking, the problem-solution format works most often, simply because it’s the way our minds most easily function — we like to identify, then solve, problems.  But pick the format that works for the issue you’re discussing, and follow the one essential rule of organization:  keep it simple and clear.