For a musician, a solid repertoire list is about as good as a resumé in some cases. If you're doing auditions of any kind you will most likely have to submit a repertoire list. It’s also necessary in some cases where the musician is working close with someone that is hiring them for a gig. For example, situations like weddings, where the musician is consulting with the bride and groom about music for the ceremony. It’s great to have a list ready. So the question is how does one build a solid repertoire list?
First off, it never hurts to be overly prepared. Knowing too much is better than not knowing enough. A great place to start when building a repertoire list is spending time finding and practicing repertoire from all of the musical time periods. (Medieval, Renaissance, Baroque, Classical, and Romantic periods) As a whole, the different time periods provide different techniques, different stylistic elements, and for the simple fact of diversity across the history of music, they all contribute to a more well-rounded working musical knowledge. If this list is for an audition, it will look great to see a musician who is well-versed in a wide variety of musical styles. If it’s for a gig, it will look great to have a wide variety of music for the person hiring you to look at. It’s a win-win. Think of it like a catalog for a business.
Another important thing to keep in mind is how to maintain your repertoire list. You will have easier pieces and you will have harder pieces, but as you develop you may consider taking some beginner pieces out and supplementing them with the more advanced pieces you're learning. Your advanced pieces are there to continually challenge you and keep you sharp. However, allow yourself some pieces that are in your ability range so you can have a sense of accomplishment. Being discouraged isn't the goal here. Honestly, some of those easier pieces are just beautiful to hear performed. Your audience will love you for it. The things to do to create your repertoire list are the same things you’ll use to keep it updated. I recommend some sort of written list or designated folder to keep your repertoire in to stay organized. That way it is easier to update as you progress. Also, when using the Suzuki method try assigning a piece to each day of the week. This will help divide the practice time up evenly and keep your practice time consistent.
This one is for free. Shoot for the moon. Find a piece or a few pieces, in addition to the pieces you're comfortable playing, that are a huge leap for you. A professor who studied at the Paris conservatory once told me it's good to hang on to those pieces that are more difficult for you. He said that you first learn them really well, and then pick them back up off and on over the course of your life to polish and perfect continuously. The benefits are nothing but good. Another scene from the movie Seymour: An Introduction, a group of concert pianist are talking amongst themselves and they mention the amount of time they've put into just one piece to perfect it for a performance. It was over the course of months with rigorous daily practice. My professor says he still works on pieces that he’s been at, off and on, for years and years. By doing this you are, at the very least, adding a shock and wow factor to your repertoire.
To sum this up, your repertoire list, when cultivated, can actually become a shining reflection of your ability. And when you're focusing on building a good repertoire list you will actually be more intentional about how you expose yourself to music, because you’ll always be looking at the characteristics of each piece and how it can help you grow.