When I ask my students about their interpretation of a piece of music, their answers are often about shaping phrases. The phrases should have some kind of beginning, middle, and end, often expressed in some kind of dynamic shape, like starting softer, growing to a louder peak, then gradually getting softer again.
That isn’t wrong, but it’s really just interpreting individual phrases. The next step is to give those phrases some relationship to each other. Does the next phrase continue the previous one in some way? Answer it? Contradict it? Make a contrast with it? If your favorite tool for expressing your interpretation is dynamics, then the answers to those questions might determine whether the next phrase, say, picks up at the same dynamic level as the previous, or at a dramatically different one.
Then the phrases should build a larger structure, such as a theme. The individual phrases that make up the theme should have beginnings, middles, and ends, but they should join together into something bigger that also has a beginning, a middle, and an end.
The themes might combine to build a movement, and the movements to form a complete work. And multiple works may even construct a complete concert program.
Small-scale phrase shaping is a good start, but mature interpretation requires thinking on a larger scale.
