How can I prepare on a topic for speech in class?

You should analyse the theme of your topic. Compress it into one topic sentence. On the basis of that sentence, elaborate your ideas. You should explain all the points. Don't leave anything vague. Your audience should also understand what you have in mind. Give examples and illustrations. But, don't

1. Formal preparation. 2. Written outline. 3. Practice. 4. Considerations.