In basic terms, the rough outline of the steps to be applied are as follows:
1) Read the case and reach a hypothesis
2) Create a storyline and build a 'ghost' presentation
3) Do more research and analysis to build out the presentation
4) Challenge recommendations/anticipate counter arguments
So far, so simple. But the real challenge is to ensure that you—whether as an individual or part of a team—are thorough.
Consider the example of one case, where one question was whether to expand internationally.
The first level of analysis is a go/no go decision on expansion
The second level is which geographic regions to consider,
The third is for the specific region—which countries to consider (and rank order them)
The fourth level is to determine the exact method of entry and how that may differ by country and also compared to the existing current model.
That level of rigor enables you to not only have a concrete, reasoned recommendation, but also to easily answer questions as to why you did not go to certain countries/regions. When those questions will come, you will be in the position of having answers which are detailed, cogent and fact-based, enabling one to demonstrate the thoroughness of the analysis
In terms of the skills required to successfully approach case studies one cannot stress the importance of analytical, effective communication and interpersonal skills, as well as having the ability to ask the right questions to elicit the information necessary to crack the case.
One needs to tackle problems from a cross-functional perspective and be a cross-functional thinker. This allows you to address a case question from multiple perspectives as opposed to your prior role or industry.
The perils of preparation
Practice is the enabler which makes one become good at filtering information, coming up with hypothesis, criteria, and doing the analysis.
Focus on the data—and only the data
The key to success is not fancy slides or groundbreaking insights but a rigorous, data-driven approach to solving the problem in a methodical and reasoned way.
Also, resist the temptation to think too big with their answers: Suggesting something dramatic in one's recommendation should be backed up by a well reasoned and developed decision.
Depending on the case, an incremental, well thought-out approach may make more sense than a drastic change.