We have a lot of books that can give you tips on preparing a speech. Your search terms are:
Public Speaking Debates and Debating
Presidential Debates (1858 to present)
Vital Speeches of the Day
This publication publishes famous speeches from 1934 to the present
5,000 full text, audio and/or video presentations of famous speeches.
Gifts of Speech: Women's Speeches from Around the World
A collection of contemporary speeches from women across the world.
Say it Plain: A Century of Great African American Speeches
Transcripts and videos of famous African American speeches from the 20th Century.
Voices of Democracy: The U.S. Oratory Project
Website devoted to study the great speeches and debates