Last time I recommended that the young conductor (even while still an undergraduate) gain experience through conducting a church choir. For the conductor who is a bit more advanced (already teaching, for example, or working in a major church position), working with a community choir or similar ensemble can be a valuable addition. The first year of teaching is most likely all any young conductor wants to do! It's an extraordinarily steep learning curve as one begins learning how to teach, how to manage behavior, how to deal with parents and administrators, organize concerts . . . well you know the drill! But at some point the conductor may wish to continue growing through conducting repertoire that s/he cannot do in their school position. At that point you might consider working with an outside choir (it could be adult, but also a children's or youth choir).
I mentioned last time that I got early experience with a church choir when I was 20 (my junior year in college). When I was 23 I started a community chamber choir, then the next year a group called the Bach Ensemble (with both singers and instrumentalists), which performed a Bach cantata the first Sunday of every month. At the end of that year I combined both ensembles for a performance of Bach's Mass in B Minor and that summer we incorporated and applied for non-profit status.
Working with any such group (a pre-existing ensemble or one you form yourself) will give you great experience: as I mentioned with the last post, the success or failure of every rehearsal and concert is up to you; you get experience with more (and different) repertoire; you may work with singers of a different ages than the ones you work with at school; and most importantly, with such a group you have to attract and keep the singers interested in working with you and the ensemble (I've always loved Brock McElheran's statement in his book Conducting Technique for Beginners and Professionals: "It's no use learning long lists of baroque ornaments if no one wants to play them under you."
Some of my fellow students also started groups at this time, but they almost always were made up of their friends at school (I sang in many of them). However, the groups rarely lasted. I always felt that when the conductor asked someone to sing, the conductor owed the singer, not the other way around. So if there was a schedule or other conflict there was little sense of loyalty to the ensemble. So when I started my first chamber choir, I quite deliberately did not ask any of my friends to sing. If they decided to audition, that was fine--they were indicating their interest in singing in the choir.
I'll say more next time about things to think about and where to find resources in starting a choir (I've started two and both organizations are still alive and thriving), but I'll end with this. When you advertise the formation of your group, you need to let people know what you're going to do, what repertoire . . . what makes you special. Think of it from the singer's perspective: why would I be attracted to this choir? why should I be willing to give up my time to sing in it?
Here's the actual flyer that advertised my first choir. I wanted to give a sense of the repertoire we'd do and the nature of the group. Until next time!