Answer:
1. Understand the proposition completely;
2. List possible evidences supporting your position;
3. Do research to support your claim and evidences;
4. Interview experts on that particular field;
5. Organize your ideas logically to preclude questions; and
6. Practice with your friends.
Step-by-step explanation:
Enough preparation is necessary but make sure you understand the issue to be debated on first. Research, experts and logical organization and presentation of your evidence will make your point truthful and convincing.