Collect contact information for the members in your section. This could be an email address, a phone number or both. The contact information should only be used to remind the members about rehearsals and meetings. It can also be useful on the day of a performance if a player does not show up.
Determine a schedule to meet with your section for private rehearsals. Give members three possible times to meet and then agree on the time that everybody can arrive. If the three options do not work for everyone, select three more until you find a time that works. It's important that you don't just tell members when they have to arrive. That sort of authoritarian leadership style could spurn mutinies.
Examine the music for your section before rehearsal. Determine problem areas in the music and be prepared to discuss, rehearse and instruct players on proper practice techniques.
Meet with the section on the agreed upon date. Make sure you remind members the day of the rehearsal. Email or phone each person. When you meet, begin with a warm-up and then work through the difficult parts of the music and the areas that have taken up rehearsal time with the band. Bring a metronome to practice the music at the proper tempo.
Discuss any problems that arise with members before they become serious issues. It is important to be attentive to how members of the section are feeling about the band. By paying attention to their needs, you can prevent problems before they begin.
Determine an appropriate plan of action for the cases when a problem does arise. If there are policies put in place by the director, you should always adhere to those policies. Being a section leader means that you have to enforce the rules of the band even if you don't agree with them.
Meet with the band director to discuss problems that can't be resolved on your own. It is your responsibility to be aware of issues in your section, but the resolution of those problems are not solely your responsibility. The band director has much more authority to settle disputes and can initiate disciplinary action for extreme cases.
Discuss with your section what is required at each rehearsal, sectional and performance. Typically, musicians will need to have lubrication for their instruments, pencils for taking notes and all required music. Also explain that they are required to practice parts which they can't play in the ensemble until they are able to.
Work individually with players that consistently are unable to perform up to the level of the ensemble. It is the section leader's responsibility to help players learn the music so that the rest of the ensemble doesn't waste valuable rehearsal time.
Determine the consequences for players that consistently do not bring materials that are required or are unable to perform with the level of the group. It is a good idea to go over these consequences with the group in the first sectional rehearsal and take input from section members.