Before performing a sound check, first initialize the mixer controls by setting them to off, flat, or zero. This establishes a frame of reference and eliminates complications later. Make sure the master volume fader is all the way down or set to zero. After powering up your mixer console and other audio equipment you may then turn on the loudspeaker power amps. You always want to power up the main speaker amplifiers last to avoid audio "thumps" when you turn on the mixer.
Before the worship team arrives, you should test each microphone and label it's channel position along the bottom of the console. Begin by having someone speak into the main vocal microphone and repeat this process for each microphone on stage. Set the input trim to unity gain. This is the point at which no level is added or subtracted from the nominal signal. Most mixers have a mark, which identifies unity on the fader and input trim controls. Check the owner's manual for your particular console for the proper settings.