Difficulties of the Introduction
People who are scheduled to make speeches are heard to declare that they know exactly what they want to say but they do not know how to begin. Another way they have of expressing this is that they do not know how to bring their material before their hearers.
Undoubtedly the most difficult parts of speeches are the beginnings and conclusions. One of the methods of preparing for delivery recognized this difference by recording that one way is to memorize the beginning and ending, the opening and closing sentences. Practised speakers are more likely not to fix too rigidly in their minds any set way for starting to speak. They realize that a too carefully prepared opening will smack of the study.
"Practised speakers are more likely not to fix too rigidly in their minds any set way for starting to speak."
The conditions under which the speech is actually delivered may differ so widely from the anticipated surroundings that a speaker should be able to readjust his ideas instantly, seize upon any detail of feeling, remark, action, which will help him into closer communication with his audience. Many practised speakers, therefore, have at their wits' ends a dozen different manners, so that their appearance may fit in best with the circumstances, and their remarks have that air of easy spontaneity which the best speaking should have.
A speaker will prepare carefully his speech proper, but leave to circumstances the suggestion of the beginning he will use. This does not mean that he will not be prepared—it means that he will be all the more richly furnished with expedients. A speaker should carefully think over all the possibilities under which his speech will be brought forward, then prepare the best introduction to suit each set.

