Conductors often like fast tempos. Very often choir directors take too fast tempos when performing with the organ. In a church setting, we have to be aware not only of the original tempo indication but also
of the acoustics of the space. If your church has huge reverberation, chances are that the tempo has to be more moderate, even though it is written allegro, vivo, or vivacein the score. If your choir director forgets about adjusting to the acoustics, politely remind him or her about that.
Conductors might forget to show when the organist should to start playing. It is not uncommon that the choir director is under a lot of stress during rehearsal or performance because there is so much to think about. Among the things that they might forget to indicate is the organ entrance. This might happen if the choir part enters after the organ. Be prepared for such situation and ask politely if they could show you the organ entrance.
Conductors might forget to show when the organist should stop playing. This issue is the exact opposite of the previous point. If the choir finishes the piece earlier than the organist, normally you would expect that choir director would show the ending for the organ part as well. However, be prepared to finish on your own. This is OK, if both of you have mutual understanding. Otherwise discuss this issue with your conductor during the rehearsal. This might save you some guessing and frantic movements in a stressful performance situation.
Conductors do not always wait for registration changes. Although the organist often has to change registration during the piece by hand, not every choir director will be aware of the challenge of this task. They might start a new episode or even a different piece without waiting for organ stop changes. If you feel that you need more time in order to successfully change your registration, politely ask your conductor to wait for you. Looking at the mirror and having eye contact always helps.
Keep these things in mind when working with your choir director either in the
rehearsal, service or a concert. As a result, your performance be more
The practical techniques of accompanying the choir with or without a conductor are discussed in Organ Technique: Modern and Early by George Ritchie and George Stauffer which I highly recommend.
By the way, do you want to learn to play the King of Instruments - the pipe
organ? If so, download my FREE video guide: "How to Master Any Organ Composition" in which I will show you my EXACT steps, techniques, and methods that I use to practice, learn and master any piece of organ music.