We should consider introductions to be a major contributor to the success of most communication. That applies to interpersonal communication, small group communication and public speaking presentations. There are questions we can ask ourselves that will aid our thinking process.
1. Who am I?
2. Who are they?
3. Why should they care?
4. What kind of "map" will the audience need?
5. How can more senses be involved?
6. What will aid their recall?
Who am I? Two people can say the same thing with different outcomes. A person that we know and trust can make the statement and we will listen, believe and attempt to retain. Another that we don't know and therefore can't trust can make the statement and we listen with doubt, fear that we cannot trust and don't want to recall it because it might embarrass us. We call those we tend to believe credible.
For example. if you are a regular church member in good standing you probably trust your leader to give you valuable and useful information which you can use to improve your life. If you are listening to a different religious leader you might not listen with the same unquestioning process and fail to either retain what was said or even consider it. Who says a thing is very important.
Include information which will aid your listener in evaluating their need to focus, question and retain what you are saying. Build your own credibility and the introduction is an excellent place to put it.
Who are they? In conversation, one on one, we take into consideration who we are talking to. That permits us to make as much sense as possible in the shortest length of time and achieve the desired result. This rule always applies no matter how large the audience. The more you know about the audience (what they know, what they do, how well they do it, what they would like to know and why) the more likely you will be able to meet their needs and expectations. We call that audience analysis and broadcasters and producers wouldn't know what to do without information about their projected audiences.
Why should they care? If there is no particular reason for them to listen to you, why would they want to spend the time and energy focusing on what you have to say. What's in it for them? That's a legitimate question and it deserves your attention. The reason they should care should be in the introduction. Make it clear and sharply focused to insure that they are willing to spend the necessary time and attention.
What kind of "map" will the audience need? Is the trip they are taking with you a long and winding trip? Or are you able to show them some direct routes to understanding. This process can be likened to a map. It has a starting point and and ending point. Along the way there will be some scenery that they can enjoy and all in all it should be an enjoyable trip. Be certain that the map you use fits the audience that is taking the trip. This going to be clearest to you when you understand how the members of your audience "mean." Remember, meaning is in us. What we are going to attempt is to create that meaning in others. That can't be done without careful consideration of who the audience is. That will include, age, sex, education, experience, income, cultural values to name some of the needed categories. This is an ideal location for your central idea as well as the main ideas you will be covering.
How can more senses be involved? Words (verbal) are detected by hearing. Speak clearly and distinctly at a reasonable pace. It is often very useful to include visual aids: photos and charts for example. In addition, you can convert your "complete outline" into short clear phrases and sentences which can become part of a visual presentation using PowerPoint or other visual presentation software. That way they can see what you are saying while you are saying it. That will involve at least two senses (seeing and hearing) making it easier to follow what you are saying. The nonverbal can be gestures and body movements that underscore what is being shown and said.
What will aid their recall? Numbered sequences, mnemonic devices and actions can be useful to aid your listener to recall what you said. For example: "There are three things that you must recall in order to. . .", "CIGARS will aid you when you are getting ready to takeoff in an airplane. C is for controls. . ." Students in kindergarten are taught letters and sound by combining actions and sounds and the process is very efficient in teaching the alphabet.
I further suggest that you take the time to write out, but not memorize, your introduction. You will find it easier to set the ideas in your mind and analyze the elements you are including. Your brain, having gone over the word choice process once, will do a better job of aiding you to choose your words when standing in front of your audience.
A well thought out introduction will open the minds of your listeners quickly and efficiently. If you lose them at the beginning, you're not likely to get them back ever. Think about what they need and what you need them to think and then give it to them as quickly and clearly as possible.