Step 1: What is your audience?
This is the first step to deciding anything about a CRM, or whether you even need one. Once you specifically know the universe of people you want to reach, then you can begin to think about how you will reach them, and finally how you can organize doing that.
Step 2: What will be your process?
Every organization has a different ladder (or path) that they want their prospects, and eventually supporters, to follow. More specifically, this question forces you to think realistically about how you will interact with your audience, and that allows you to get a better picture of what you need.
e.g. You know you will be doing a lot of offline organizing, and you need a CRM that supports that part of your operation. This type of information is critical when trying to find your solution.