It is a very complex subject, because you study the scores all your life. And inevitably, each one of them will have to be conducted for the first time or played for the first time. There is the initial process of absorbing a work of art, all the information that is in it, in the score itself, which means the notes, the indications from the composer. Sometimes there are few, as in early music, and sometimes there are very many as in the music of later composers, Mahler, Strauss, etcetera. But it means absorbing all of that information and researching the composer and the period in which the composer lives or lived as well.
In a way, it is simpler with contemporary composers because they live in the same world in which we do. And even if we perceive it differently, it's still the same world. But with earlier composers, you have to try to imagine a world which is very different from ours, without forgetting that human nature never changes - how it manifests itself will be different, but human nature itself is the same. Nevertheless, those ways influence a creator. And so, it is researching and trying to sort of travel back in time. And all of that has to begin when you first approach a piece of music. All of it before the first rehearsal, because the first rehearsal may be your first with that piece, but not necessarily the first for some, or all, of your colleagues.
As the leader, your role is to have a vision of the piece and share it with your colleagues. Naturally, as you are making music with others, the vision evolves. It's as if you start with the trunk of the tree, which is what you bring, and then the branches spread. The more they spread, as a result of what others bring to it, the richer the interpretation will become. But that initial vision has to be there, otherwise, you have no right to stand on the podium.
That is the first step. Later, while living with the piece all your life, you will never stop learning about it. It has so many possibilities for expression! The work remains the same, but we are the ones who change as we go through life. There is no limit to how much we can discover in those creations. That is completely inexhaustible.