Write a few sentences describing your overall topic. Then write an additional 2-3 sentences describing each of your main topics. You will end up with about 4 main topics.
I. Intro
II. First main topic
a. Subsection 1
b. Subsection 2
c. Subsection 3
III. Second main topic
a. Subsection 1
b. Subsection 2
c. Subsection 3
IV. Third main topic
a. Subsection 1
b. Subsection 2
c. Subsection 3
V. Fourth main topic
a. Subsection 1
b. Subsection 2
c. Subsection 3
VI. Conclusion
For Example, here is a main topic and 3 subsections:
V. Roman Engineering
a. Pantheon
b. Aqueducts
c. Coliseum