FileMaker is as much a problem-solving tool as it is a development platform. As such, it provides you with the means to achieve a wide variety of ends (and in the process, solve many problems). How you use the tools FileMaker makes available is less important than the functionality your solutions are able to deliver. Nevertheless, considering the underpinnings of a well-formed relational data model is helpful — not so much so that you will be bound to adhere rigidly to it, but so that you'll be able to make informed choices about how and when to depart from it.
Regardless how you choose to work in FileMaker, you need a clear plan for the storage of data, including the main connections and interactions between different data types. This over-arching plan is your data model. It doesn't matter where it exists — it could be in your solution itself, on a whiteboard in your office, on a diagram in your diary, or a vision in your imagination — but without it, little will work well, and your solutions will quickly become mired in confusion and complexity.
A data model's purpose is to establish clarity and simplicity, enabling you to see — from any vantage point — what belongs where, and how to bring together the available elements to achieve required outcomes.
Modern database applications — including FileMaker — take a set of ideas based on the theoretical work of Edgar F. Codd (first made public in 1970, while Codd was ...