Good public speaking should use attention gaining devices. Here is one that works every time: Virtually every speaking presentation I do, I find some excuse to get someone on stage with me. When an audience member is on stage, the rest of the audience is glued to the action for the following reasons:
1. They want to see what is going to happen to one of their own.
2. They are priming themselves to be up there.
3. They are worrying to death that they may be asked to be up there.
Reasons 1 and 2 are good and reason 3 is not so good. For 1 and 2 the mindset of the observing audience member is that, "I want to watch to see what my colleague or other audience member will do when they are on stage. No matter how exciting you are as a presenter, you cannot compete with the excitement generated by someone who is on stage who is not "supposed" to be on stage.
The other mindset is, "I BETTER watch what is going on in case I am asked to go up there." This mindset is good too, because it forces the audience member to actually think about the point you are trying to make.
For number 3, you want to keep shy or sensitive audience members from withdrawing from your program altogether because of the fear that they may be asked to stand up in front of everyone. This chance of withdrawal is easily eliminated by the following statement:
In a moment I'm going to ask for some / a volunteer to come on stage with me. Don't worry. No one will have to come up if they don't want to.
If you have a high percentage of shy audience members, you will almost feel the breeze as they breath a sigh of relief.
Now we will take a look at what things you can do with them once you get them on stage. According to a study done at the University of Wichita, public recognition is one of the top motivators of people. If you claim to be a "motivational" public speaker of some sort, it might be a good idea for you to use your highly public profile while you are speaking to give out public recognition. I find out the good things that particular audience members have done during my extensive pre-program research.
Here are some ways to use the information you learn:
Recognize a single audience member for a particular achievement, or for a period of high performance.
Recognize a group of audience members for a particular achievement, or period of high performance.
While they are on-stage make a custom visual highlighting their achievement, or performance (If you use an overhead you can give it to the audience member or team after you show it. Do not forget to include your company name at the bottom of the visual. Many times these will be hung on the wall in the organization which will give you free publicity).
Another reason to get an audience member or group on stage is for some sort of demonstration. I do one where I'm demonstrating personal space across cultures. The person helping me gets a good laugh from the audience as we interact.
Try to have pre planned ad libs ready to go for many of the comments or questions you anticipate from the people on stage. You can also have someone on stage to assist you in writing on the flip chart, changing overheads, or to blow a horn when someone in the audience asks a good question. Use your imagination.
Whenever, someone is up there to assist you, make sure you give them some kind of prize. One of your products is usually good because it gives you a chance to mention it without using a hard sell. And just about always lead the audience in a round of applause for the helper as they return to their seat.