It's hard to answer your question without knowing the following information:
- The measurable objective of the case
- The context of the case
- Any other questions that will remove ambiguity (e.g. entry mode)
In other words - a lot in your structure will depend on the clarifying questions.
For example, you need to understand at the beginning of the case what are the entry options. E.g. if you have money to acquire someone, very early you should be looking for concentrated markets and big players to acquire. If the company plans to enter organically - you should be looking at fragmented markets.