Understanding unknown storage structures
More often than not, light systems (those not embedding a full-fledged OS such as Linux) will have a pretty well-documented way of storing their firmware internally (since this storage form is crucial for the target MCU to function properly, it is well described in the target MCU datasheet). On the other hand, the way the data is stored by the firmware itself is very much left to the firmware developer device.
Unknown storage formats
There is no definitive way to reverse engineer the way data is stored, as for most reverse engineering, it is as much an art as it is a science. The only way to get a good knack for it is, just like soldering, doing it again and again, but having spent a fair share of my time reversing a lot of different things, such as network protocols, storage structures, and more, I can give you some pointers.
Understanding the way the data is organized for storage depends on multiple factors. There are some general...