Secure sound equipment. Floor mics should be properly taped down and marked so performers will know where they are, but the audience will not be distracted by them. Ensure that sound monitors won't be easily kicked off the stage or turned over. Speakers should be stacked at appropriate levels. Tape down all wires that are in high-traffic areas. And pay attention to wireless mics, especially ones on the more mobile performers. There's nothing like a dropped wireless mic to distract an audience!
Learn the soundboard functions specific to each microphone and speaker. Technical specs can vary, so if you learned how to run sound on one board, it doesn't mean the process will be the same on another. Be sure to label each knob for appropriate adjustments within the show should something go wrong, like feedback or a disconnected wire.
Test sound levels for each and every microphone. Have a volunteer say words full of "s" and "p" sounds into the mic to check for clarity. Repeating the same word over and over will allow you to check for volume. Try to eliminate as much hiss as you can. Sometimes, the hissing sound is a matter of conflict between the specific microphone volume and the master volume of the board. Adjust these appropriately.
Check sound levels for the speakers and monitors. Have one volunteer stand in different parts of the venue while the other makes loud and soft sounds into all microphones. Be sure to pay attention to the back corners of the venue as well. For monitors, you'll need the volunteers to play instruments or sing at the same time to see if someone's sound is coming through louder in a monitor than another one's.
Mark sound cues on a cue sheet or script. Be sure that all labels and directions are clear and match the labels on the sound board. Check each cue for accuracy. Label makers eliminate the need to translate someone else's chicken scratch.