Context colors every situation. In an article for Business 2 Community, Jannike Ohsten discusses how to build a business case and how to tailor it to your unique situation.
Every business case features these essential elements: the rationale for how the project will solve a problem, alternative options to the project, pros and cons that show why this project is the best option, the costs of not conducting the project, the risks involved in conducting the project, and an explanation of how those risks will be manageable. But beyond this, you then must consider who will actually be reviewing the business case.
It should be clear in the writing why this project should matter to the reviewer and how this project will align with business strategy. Likewise, use language that will make sense to that person and avoid fluffy jargon. Well-researched facts and figures are often the most persuasive element of a business case, so try to include as many as you can.
You can view the full article here: http://www.business2community.com/strategy/write-persuasive-business-case-01138218