To start your oral presentation, you need a hook -- something to grab the audience's attention.
Maybe you could say, "Would you like to know how to change a $30 grocery bill into a $3 grocery bill? It is possible. There are great online communities that can help you do just that."
You will have the interest of your audience and they will be eager to learn more.
For your conclusion, you can refer back to the "hook" with, " So, now you know how to magically change $30 to $3. More money in your pocket. I am confident that all of you can be a skilled couponer in no time."
I hope this helps.