Prepare the microphones. Before setting anything, make sure the microphones are in the proper channel and that wireless microphones have full batteries.
Prepare the vocalists by making sure they have their designated microphones. Ideally, the vocalists should be testing their microphones in the positions at which they will be performing.
Place yourself in a location to hear the full sound. In a recording setting, this may simply mean putting on headphones while at the sound board. In a live setting it means placing the sound board and yourself in a location to be able to hear the house speakers well, receiving the same sound as the audience.
Set each microphone individually. Be sure no other instruments are being played and that other singers are not singing into their mics while you are doing this. This can throw off what you are hearing as you set a vocal.
Have the vocalist sing into the microphone as you listen carefully to the tone and resonance of the voice through the system. Unless the vocalist is singing a bass or alto part and heavy low tones are needed, be sure the HPF (high pass filter) button is down.
Attempt to achieve the most natural sound possible, using the high, middle and low frequency knobs located on the microphone channel. As you listen intently to the vocalist, adjust the high frequency knob to enhance or lessen the light tenor tones in the voice. Adjust the middle frequency knob to enhance the normal resonance of the voice when pitched at the singer's most comfortable middle range. Adjust the bass frequency to bring out or lessen the voice's low tones.
Continue to make adjustments to the three frequencies as the vocalist sings low, middle and high notes in his voice range, to ensure that the sound is set to accommodate the pitch changes in songs.