My name is Manuel Diewald and I am a Sydney based guitar teacher in West Pennant Hills who is in his final year at the University of New South Wales studying music with a stream in Pedagogy.
Figuring out which pieces to learn can be quite tricky, especially if you want to create a contrasting performance that incorporates many different styles and eras of music. Ultimately, you should play pieces that you enjoy which seems like the obvious choice. I mention this as I have come across students who have learned pieces just because their teacher suggested them. Having said that, your teacher will be a great source for new repertoire to learn which is where I have sought after much of the repertoire I have played. So what are some things to consider when choosing pieces to play?
Enjoyment
The first reason for picking any piece to play in my opinion is that you enjoy playing and listening to them. To really delve into the musicality of a piece I feel you must make a connection with it which enables you to express how you are feeling when you perform it or even listen to other inspiring recordings. Some pieces will probably be more enjoyable than others but a program you choose should excite you from start to finish or else it will be difficult to convince an audience of your musical choices.
Contrast
I feel that the choice of someone's repertoire should be contrasting in some way, whether that's from a varying style of genres, techniques or moods. For example, you may want to create a program that stems from one culture or style like South American music or Australian music. That may seem like there is no contrast though within that program you can vary the moods of each piece which can stem from different key signatures, rhythmic feels and tempi to name a few.
Challenging
In some aspects of your repertoire, I feel that it should challenge you which for the most obvious reason can improve your technique though mainly to give you a goal to set towards. This does not and probably should not mean that the whole repertoire is so challenging that you are left overwhelmed as there are many simple pieces out there that are beautiful and appropriate as concert material. Picking some pieces that challenge you keeps you moving forward with your technical progression and allows you to explore a range of other pieces that you may not have been ready for, expanding your repertoire choices.
Whatever your choice of repertoire, it is entirely your choice and I only give these tips as suggestions in hopes that it sparks some interest to anyone reading this. I suggest going out of your comfort zone and learning new styles of music that you haven't played or listened to before. You never know what may cross your path if you don't open your mind and explore the vast amount of music that is so readily available to us.