If you are going to be part of a concert and you are going to be part of the chorale, you need your uniform so that you can start playing. You also need transportation because how can you get to the location when you do not have the right vehicle to use to get to your location.
You also need to get your music memorized because how can you sing the songs when you do not know the words of the song. Some chorales would allow you to bring music sheets but most chorales will require you to not do anything. You may also need to have the right hair in order to coincide with the rest of the chorale members.