I like to set up multiple microphones during a live P.A. event. I have one microphone on the stand plus one for the dj booth. I spread out the speakers as far as I could to cover more ground. I do not put the speaker at full volume. I typically put it at 50 percent and max out at 75 percent.
More often than not there are different people who speak at different volume levels. Every time someone speaks, you may have to adjust the volume based on how loud they talk into the microphone and how close they have it to their mouth.
Also it is a good idea to tape down the cabling and wires. I always do a sound check before I tape anything down in case I have to use different cables or a different microphone. It is good to have more than one extension cord in case one needs more cord to reach the power.
I use microphones that are always on, but I am able to turn them on or off from the mixer I use. It is good to turn them off when people are talking to each other before the ceremony not knowing it is on, because the audience can be able to hear them talk other business.
Also it is good to be aware of how hot it is. Certain speakers may have issues since it is really hot. It is good to keep speakers in a shaded area and if not some speakers have weather proof covers. It is good to take an extra speaker, since the elements may cause the speaker to overheat or get wet. Heat can be an enemy, but also rain can be a party pooper.