John Bright
You can profitably study the speeches of John Bright. They are noteworthy for their simplicity of diction and uniform quality of directness. His method was to make a plain statement of facts, enunciate certain fundamental principles, then follow with his argument and application.
His choice of words and style of delivery were most carefully studied, and his sonorous voice was under such complete control that he could speak at great length without the slightest fatigue. Many of his illustrations were drawn from the Bible, which he is said to have known better than any other book.
Lord Brougham
Lord Brougham wrote nine times the concluding parts of his speech for the defense of Queen Caroline. He once told a young man that if he wanted to speak well he must first learn to talk well. He recognized that good talking was the basis of effective public speaking.
Bear in mind, however, that this does not mean you are always to confine yourself to a conversational level. There are themes which demand large treatment, wherein vocal power and impassioned feeling are appropriate and essential. But what Lord Brougham meant, and it is equally true to-day, was that good public speaking is fundamentally good talking.
Edmund Burke
Edmund Burke recommended debate as one of the best means for developing facility and power in public speaking. Himself a master of debate, he said, "He that wrestles with us strengthens our nerves and sharpens our skill. Our antagonist is our helper. This amiable conflict with difficulty obliges us to have an intimate acquaintance with our subject, and compels us to consider it in all its relations. It will not suffer us to be superficial."
Burke, like all great orators, believed in premeditation, and always wrote and corrected his speeches with fastidious care. While such men knew that inspiration might come at the moment of speaking, they preferred to base their chances of success upon painstaking preparation.