Some people suggest that the memorandum is simply another form of letter, except that the communication is internal, within the company. Idea development may parallel letter organization. Include a clear, definite statement of purpose. Including a verb helps give sense of direction.
Opening paragraph is important.
Supply definitions if needed. Entire body of memorandum includes sufficient reasons for action recommended. Evidence for recommendation include examples, statistics, analogies, quotations, charts. Usually one paragraph for each major issue or conclusion. Transitions are used to move ideas along.