Read the entire essay. Highlight what you believe are the main points of the essay. If the essay is anecdotal more than point-driven, select the main ideas of the stories.
Jot the main points in a notebook or into a computer word processor. If you are working on an essay regarding an idea for political reform, for example, discard any points that may muddle the memo, that is, that are not as strong or well-researched as other ideas.
Create an outline. Form a framework, or skeleton, for how you want the memo to take shape. Some memos read like essays, in form and content, but are more biased and objective.
Organize the main points in a chronological, analogical or systematic approach. Keep your reader's attention span in mind. Give them a shocking, or inspiring, first paragraph or line. Then, pare down until the next major point or idea.
Compose a rough draft. In the margin, include any ideas that come to you that were not present in the essay. If this is for a class or business assignment, get permission to add points not included in the original essay.
Drive home your points. When you make a point in the memo, or describe an idea you feel is vital to share, make sure you communicate that enthusiasm to the reader. Use short, clear, well-written sentences.