Effective speechwriting means being aware of all human factors. Remember that the “public” in “public relations” refers to an audience of real people. Nowhere is that more immediately apparent than when speaking before a crowd.
Martin Luther King had a dream, one intended for the audience of his day. Yet there are few that haven’t heard of his famous speech. Your potential audience is infinite. However, you should write first for your intended audience and second for your potential audience. Ask also whom your audience relates to? Try to write in safeguards against possible negative reactions. Your audience may go away certain how they feel about the speech. By the time they share it with others and they regurgitate it back, who knows what they’ll believe they heard?
Armed with a feel for the participants, you’re on your way to effective speechwriting. The first layer is purpose. The purpose of your speech has either been given to you or you have had to develop it. Write out this purpose, analyze it, and distill it until it’s clear and precise.