A few tips and tricks to take from the impromptus
Graft that structure onto a simple INTRO - BODY - CONCLUSION template
Whatever your topic and no matter the speaking occasion, aim to offer the audience a clear intro and conclusion, with the body organized according to the pattern you've selected.
No matter what, offer a CONCLUSION
Not "Okay I'm done" but
sum up/review your main points.
Not "That's all I got" but
close with an interesting quote or lesson learned or final thought.
Don't just end the speech after the body
If you're really at a loss for a conclusion, wrap up with a simple "Thank you for your attention."
At a total loss for words? Tell a story.
Choose and use visuals wisely
Visual aids should complement/enhance your talk, not distract from or undermine your message (or your authority and credibility as a speaker).