Any public speaker has to get his audience's attention within his opening remarks. Failing to do this will lose the audience for the remainder of the speech. There are several ways of achieving this. It can be done with a bold or controversial statement, like a question that gets the audience thinking and on their toes. Once their attention has been grabbed, it must be held; that is done by being passionate about the subject of the speech, which means you have to know the subject matter. A personal touch is always good -- a speaker is always more believable if he has experienced what he's talking about.
Half of the battle in public speaking -- whether the speaker is a politician or an Arctic explorer -- is to know the audience and to plan the speech so that it relates to them. Knowing just who is there in the audience listening to you is an important responsibility of any public speaker. A speech filled with statistics and data falls on deaf ears if the audience is a group of teenagers. In the same way, a speech on video games may be lost on a group of accountants. If the audience is to be, for example, a local ladies club, find out about them and what they do before planning the speech; then plan it in such a way that they are fascinated at how you knew certain facts.
Having grabbed the audience's attention with the first sentence, it is the public speaker's responsibility to keep that attention. This is done in a number of ways. High on the list are eye contact and the use of gestures. Keeping eye contact with the audience is extremely important -- they lose interest if the speaker is just reading his speech with eyes focused down toward the podium. Browse the audience, occasionally picking out an individual and making direct contact. The use of emphatic gestures is another way of emphasizing various points in the speech, as long as the gestures do not become mannerisms.
One of the first things to be taught at any acting school is how to project your voice. This means speaking in such a way that the words can be heard and understood at the back of the theater, even if they are whispered. It is a public speaker's responsibility to be heard at the back of the venue. Voice projection is achieved by the efficient interaction between lungs, diaphragm and intercostal muscles, and is a quality that has to be practiced over and over again. Part and parcel of voice projection are enunciation, articulation and pronunciation, which are qualities that also have to be practiced.