Identify the main tasks laid out by the study guide that your teacher handed out for the exam. If your teacher didn't hand one out, generate broad ideas from your class notes and readings, and try to anticipate the questions he might ask.
Write each separate task or idea inside of a bubble in the middle of a blank piece of printer paper, using a separate piece for each. These can be whole questions from the study guide, the individual parts of multi-part questions or just the overarching themes of the relevant class material.
Draw lines out from the center circle, and write more specific ideas that relate to the bigger picture or task. Circle these new ideas, and try to be as general as possible.
Break down the circles from Step 3 into smaller ones by drawing more lines. Try to have three to four smaller circles for each larger one, and spend an adequate amount of time brainstorming to fill the page. Look in your class notes for more material to use.
Write in factual information, in a different color, once your ideas get specific enough to warrant evidence and support. This information should be relevant to your answer, and should be from material presented on or talked about in class.
Work backward and connect the facts and small ideas to arrive back at your main circle. Follow and connect different routes using different color highlighters to find unique solutions.
Flip the paper over, and translate your routes into complete sentences. Each path should be its own section or paragraph, and you can connect these paragraphs to form the rough draft of your essay.