A rehearsal is meant to prepare you for a service, and the preparation for that rehearsal needs to begin far before rehearsal time.
When rehearsal ends, do you feel calm and ready for the service, or are you in a frantic state of fixing, changing, running around, and praying that everything goes significantly better than you're assuming it will?
Make a setup checklist, and include on it things as mundane as "confirm each musician has a music stand."
While you're never going to get everything right all of the time, running a smooth rehearsal isn't as out of reach as it seems.
The single most important way to ensure a productive rehearsal is to prepare for it in advance.
While it is such a simple concept, it is one that gets lost on so many of us.
I'm not just talking about being sure the sound system and projectors are turned on, but instead preparing for the countless tiny things that slow down rehearsals or keep them from starting on time.
What are the little problems in your rehearsals that recur week after week that could have been fixed when you were setting up? For us it's not having instrument cables ready to go with each direct input; it's not having the worship leader's mic loud enough in the choir monitors; it's having a different lyrics roadmap in ProPresenter than the worship leader planned on singing.
If you're the team that's known for consistently not having prepared, then work hard to identify those trouble spots and write them down.
Really, put them on actual paper.
Make a setup checklist, and include on it things as mundane as "confirm each musician has a music stand." This will help you prepare consistently and it will also be a guide for anyone filling in for you.
Depending on your church's schedule, a great time to prepare for weekend services is Friday. Fridays are when we check most of the items off of our checklist: double-check lyrics and ID slides, replace lamps that are out, and do a final check of the stage and consoles to be sure everything is set up correctly. Our checklist is two pages long, and even though we have most of it memorized, we still print it out and check the items off every single week.
Next, be sure you know how to communicate with the band, and when the appropriate time is to do that.
Front of house audio engineers, I'm looking at you!
You may be in a role where you have the authority to act as a producer, and if so, have a conversation with your worship leader about how he or she best responds to your constructive criticism. Whether it's between songs privately in rehearsal, or through a talkback mic to the entire band, it's critical that everyone knows that you've been given authority to offer comments to the band and vocalists.
If you do offer comments, offer them gracefully, in the same way that you'd like to receive comments about your mix. Offering your comments during rehearsal in the way that you and the worship leader have previously agreed upon will help build trust between the stage and the booth.
Rehearsing songs isn't the only part of rehearsal.
Transitions between songs and out of songs, into speakers, videos, and other segments are often done for the first time during the service, and that's not the right time to be perfecting those elements!
Try to build in time for a full run-through after the band and production team have rehearsed each individual song. Transition rehearsals will help every person on your team with their cues, whether it's unmuting mics or beings sure the stage is lit correctly.
Since it's unlikely to get people such as your pastor to attend rehearsal, have someone step in for him. Even a 10-second "I'm the pastor and this is where I'll stand during the sermon," can be sufficient for the production team to understand how one segment of the service flows into the sermon.
It can be difficult to find time for a full run-through; it took us years to get to the point where we could do it for one of our services, and we have other services that still do not do a run-through. Work with your worship pastor, band leader, or whomever else to determine whether how the rehearsal is run is most efficient and beneficial in order to cover all of your bases.
You may find that musicians need to be practicing more at home prior to rehearsal, or that the production team needs to arrive 30 minutes earlier each week to get set up. Identifying those areas may help you uncover the extra time you need to do a full run-through.
When you're finished with rehearsal, your team is going to have a lot to do. Final checks on cleaning up the stage, looking at battery levels, fixing lyrics, touching up lighting cues the list goes on and on.
If you can, though, take some time to build community with your team. For one of our services, we sit down to read the pastor's scripture text from a few different Bible translations, and then take turns discussing in just a few sentences what stood out to us in that passage.
Psalm 51:10 (ESV) says "Create in me a clean heart, O God, and renew a right spirit within me." My guess is that you won't have time for a full-on Bible study before your service begins, but even that 5 or 10 minutes preparing spiritually for the service can put your team in the right frame of mind to serve with a right spirit.
After all of this, you should feel relaxed and ready for the service to begin. It's worth noting that your schedule may not allow for you to be relaxed!
Many churches are like ours in that they have two completely different services back-to-back, in the same room, on the same morning. For us, that means the band has 15 minutes to get on stage, plug in, get sounds, rehearse songs, and be done. Half of what I wrote above is out the window for that service! But if anything, we prepare even better in advance for that service, because we know we won't have a second of extra margin.
And if you are fortunate enough to prepare well enough to have some newfound margin, you'll find yourself in a much better spot to make any last-minute changes. After praying with the band, the worship leader may decide to add another song. Great! Your team finally has the margin to prepare those lyrics without breaking out into a sweat!
A great rehearsal will help lead to a great service. So spend some time during the week to do whatever you can do to prepare for that rehearsal!