My choir also practices on Tuesday evenings. We practice for about an hour (unless it's the practice right before our worship service, which may last 90 min)
Since my church has various choirs that are assigned a particular Sunday, each choir has four weeks to prepare for their worship service. During that first rehearsal, after prayer and scripture (usually), I'll share with the choir members what God has shared with me in terms of the needs of the people. (We've finally gotten to a place where the choir members are beginning to sense where God is taking us and, it's awesome and helps them to understand song choices.)
During this rehearsal, I'll introduce the songs for the upcoming service and give them CDs that I've made for them (a great investment if you are a director, because it allows the spirit of the song to get into your choir members.) I've found that, since the members belong to more than one choir, or may be on the Praise and Worship Team, it's not good to give them all new songs in a month.
Anyway, that first rehearsal we work on notes and the message of the song. In the following rehearsal, we'll continue to discuss the message and fine tune it (dynamics, diction, etc)
That's how rehearsal work for me, and God has been moving mightily, as of late.
Jonathan
