As you have seen, OAM and SMS use a variety of conceptual structures through which you can describe your business environment and specify a storage management policy. Furthermore, each of these structures offers a significant amount of flexibility.
Unless your business environment is an unusually simple one, you should expect the analysis process to require several iterations. There are likely to be several equally viable ways to define your Object storage groups and classes. Unfortunately, there are no magic algorithms for choosing which approach to implement. That decision can be made only by one who knows the most about your business: you.
At this point in the planning process, you should have a rough idea of how your objects are to be organized into Object storage groups, collections, storage classes, and management classes. The next step is to analyze your processing environment.