Create a live sound effects table. Use this to produce live, basic sound effects from backstage. This option is best for small stage productions or any situation where sound is produced from the stage without amplification. Use a secure table--one that won't wobble--and stock it up with objects that you can use to produce sounds, like dropping objects, footsteps--use real shoes, horse hooves--coconuts--or gun shots-a wood slapper.
Perform any stage combat sounds onstage. For safety's sake, stage fighting is choreographed so that mimed punches, slaps and kicks don't really physically connect between one actor and another. Because of this, sounds need to be created through some other means to complete the illusion of fighting. For best timing, have the actors create the sounds during the fight by slapping their hands together--if the sound is created by the “victim”--or clapping a hand against the chest or thigh--if the sound is created by the person throwing the punch or slap.
Assemble pre-recorded sound effects. Either record your own--do this only if you have good quality microphones and sound equipment to get a sound that's close to real life--or find stock recordings of common sounds. You can find many of these for free on sites (see Resources), but for high quality sounds and wide selections, you might have to pay on some sites. You should also check out some leading sound libraries, such as the BBC sound library--a gold standard among sound effects designers--their CDs are often available through public library collections.
Feed recorded sounds through the same PA system as the actors' microphones. Use a playback device that can guarantee instant playback, such as a digital multi-track recorder or a computer sound editing program--do not use a CD player. Practice sound cues in rehearsals during tech runs.