When something can be read without effort, great effort has gone into its writing."
-- Enrique Jardiel Poncela
You've gone from an idea, to research, to a pile of random notes, to categorized notes. You're now ready to start planning how the essay will fit together.
Formal essays differ from informal essays in several ways, most of which will be covered in the section on writing. During the planning stage, you need to know whether or not the essay is going to be a formal one. If the teacher or professor didn't specify, they probably want it to be formal. An informal essay is one that doesn't necessarily rely on structure to make its point, such as an essay explaining how you personally feel on a given subject, or what you did last summer. Formal essays must have an underlying structure that makes sense so the reader doesn't have to wonder where you're going with your points.