A sound check can be your best friend, or it can lead to a lot of stress (both for you and for the band). For the church sound volunteer, this is a make or break time. A well run sound check puts everyone at ease, gets your levels set up properly and dials in good monitor mixes for the band. A poorly run sound check will get everyone aggravated, add stress for the band, and set you as the FOH engineer up to fail. Obviously, the former is a more desirable outcome, so let's consider a few ways to get there.
Nothing will put you farther ahead in the sound check game than arriving early. Get there early to go over the set up, line check, label the board, check the monitors and generally make sure everything is ready. Scrambling to figure out why the bass is showing up on the click track channel will not make sound check go smoothly.
Know Your Setup
Have an input list. Label your board. Make sure you know which aux sends go to which monitor mixes. Figure this stuff out in advance, not when the band is standing on stage starring at you. Remember, planning will set you free.
Know the Musician's Names
This is a little thing, but it makes a big difference. Instead of saying, "Hey bass player, can you play your, uh, bass please?" you can say, "Steve, give me some love on the bass!" People like to hear their name. Label the board with their names if you have to. And don't forget to say thank you when you have enough from them. Instead of barging on to the next instrument, try this, "Thanks, Steve. Justin, can you play a little somthin' somthin' for me, please?" This helps, I'm not kidding.
Use a Talkback Mic
Again, small thing, big difference. If you don't use a talkback, you have to yell to be heard. Do you like to be yelled at? Didn't think so. Neither do musicians. Plus, if you work the talkback mic correctly, you can get your Barry White voice on and sound all smooth and cool. That makes you sound like you know what you're doing. That is a good thing.
Proceed in an Orderly Manner
Instead of bouncing all over stage, run the sound check the way you'd build a mix. Drums, bass, guitars, keys, vocals. It's not a bad thing to start off on stage and tell everyone what you're going to ask for as well. Then they know what to expect and things will move faster.
Make Sure They Have What They Need
This is especially important if the band is using Avioms, PQs, HearBack or whatever. Don't move on if they're still dialing in their mix. It's not a bad idea at the end of sound check to stop and ask, "OK, I got what I needed, are you guys all good?" Goes a long way.
Don't Mess With It When You're Done
This is a biggie. Once you get the gains and EQ dialed in, don't mess with it too much. I say too much because quite often, musicians won't play as loud or sing as loud as they will later on, and you'll need to back off the gain a click to avoid overdriving the preamps. Or you could give yourself some room just in case. Either way, try not to mess with it. Same with EQ. Tweaking EQ all over the place will radically alter the sound in their ears, and make it sound like you're changing gain. So get that dialed in early, then "freeze" it. Again, if you need to adjust slightly, do so. But don't suddenly take 6 dB out at 800 Hz and expect to not get noticed.
There are a bunch of other tips I've picked up along the way, but those will wait for another day. Happy sound checking!