Also, consider what you want your reader to learn. What kinds of questions do you need to answer? Try brainstorming to come up with every aspect you want to know about your two subjects. Then go back and look for connections between the two. You will want to come up with a thesis after brainstorming in order to figure out what the crux of your paper will be. A solid thesis statement for a compare/contrast essay should mention both topics and give the reader some idea of where your paper is headed.
Your last step of prewriting work will be creating an outline. Outlining will help you organize your ideas and make sure that you give both subjects, A and B, enough consideration in your paper.
There are two ways to organize a compare/contrast paper. The first option allows you to write about your first topic in your first body paragraph, the second topic in your second body paragraph, and then start a new paragraph analyzing both of the topics. The second option allows you to write about all the similarities between the topics in the first part of the essay and all the differences in the second part.
1. Paragraph 1: Introduction
2. Paragraph 2: Topic 1 (Comparison a)
3. Paragraph 3: Topic 1 (Comparison b)
4. Paragraph 4: Topic 1 (Comparison c)
5. Paragraph 5: Topic 2 (Contrast a)
6. Paragraph 6: Topic 2 (Contrast b)
7. Paragraph 7: Topic 2 (Contrast c)
8. Paragraph 8: Conclusion
9. Paragraph 1: Introduction
10. Paragraph 2: Comparison a (Topic 1&2)
11. Paragraph 3: Comparison b (Topic 1&2)
12. Paragraph 4: Comparison c (Topic 1&2)
13. Paragraph 5: Contrast a (Topic 1&2)
14. Paragraph 6: Contrast b (Topic 1&2)
15. Paragraph 7: Contrast c (Topic 1&2)
16. Paragraph 8: Conclusion