Figure out what you will be recording that day, for instance, vocals and instruments, and decide which mics you need for which application.
Go into the room where instruments will be recorded and have guitar players or horn players play their instruments and use your ears to find the best-sounding spot for mic placement.
Try to get mics as close as possible to guitar amp or bass amp speakers for a "close-up" sound, or further away to get more of a "room" sound.
Try to get mics as close as possible to drums and further away for cymbals, to prevent them from overpowering the mix. A dynamic mic for each drum, and two condenser mics above the set, pointed down, is the norm for a good drum mix.
Place a "pop" filter over the vocal mic to prevent popping and sibilance from overpowering the mix.
Have the vocalist sing into the mic while listening from the control room. Set the mic so that the vocalist's loudest notes stay below the red line, or distortion level.
Have any guitar players, horn players and drummers each play their instruments and set their mics accordingly, insuring that their input volume stays well below the distortion level.
Hook up a pre-amp and compression to the vocal mic to get a warmer, tighter sound that cuts through the mix. Though effects like reverb are usually added later, some vocalists like to hear reverb in their headphones when singing. Most mixers are equipped to allow effects without recording them.
Have the entire band play a song or several songs and ensure that all levels are equal and all players can hear their own instruments in the mix. Adjust accordingly.
Play the recording back and ensure that all levels sound good and are at high volume, but below the distortion level.