Structure your speech for maximum impact

“Tell them what you’re going to say.  Say it.  Then tell them what you said”
 
And that is so true!!  We have such short attention spans.  And so do audiences.  If we want to make a point that will stay with an audience after they leave the room, we have to repeat and reinforce it throughout the presentation.  
 
Introduce your well defined theme.  Present that theme.  And repeat it to conclude.

You will have given your audience a great chance of remembering it.