Clean out a closet or small room in your home or at a recording studio to make a simple recording booth. Remove everything from the space to prevent tripping or sound waves bouncing off of stuff, which will affect the sound being recorded. Consider using an unused bathroom for a simple recording booth.
Place sound-deadening material on the walls of the booth. Remove the shower curtain if using a bathroom and make sure that any glass or mirrors are covered to minimize audio sound reflection. Use professional sound-deadening materials if you can afford it, or carpet remnants on the walls of a closet, which will allow you to control the reverb and delay used through outboard gear or software.
Move audio recording equipment near the room for convenience or run a snake to the room. Keep the recording gear close, but not in the booth since it may create feedback and unwanted noise. Run the cables through a hole in the door or wall so that the door of the room can be completely closed without interference for dead sound on recordings.
Run power to the room if there is none present. Most closets do not have power, so running an electrical cord with a power strip will allow you to plug in amps and other devices in the room for recording. Use the booth for recording vocals or instruments using the power strip, but keep the wires carrying power away from the audio cables as the electricity may cause unwanted noise in the signal.
Place a dimming light fixture in the room. Lighting can cause sound interference, so place an alternate lighting source in the booth that can be dimmed very low so that you can still see, but will not be too intrusive. Many vocalists prefer dim lighting to set the mood as well, so it is a good idea to add the fixture.