Position the master control desk in a central location. This desk holds your hardware mixer or computer, and is the center of your home studio --- everything you record in the studio flows through this location. Ensure that you have enough electrical outlets nearby to plug in your mixer, computer and other recording devices.
Place one monitor speaker on either side of your mixer or computer. Turn the speakers inward so that, if you draw a straight line out from each speaker's face, the lines intersect at the point at which you're sitting. If space is an issue, consider using a pair of monitor stands to elevate the speakers above the master control desk.
Set up any other equipment that you'll need to access while recording within easy reach of the mixing desk. If you're using a hardware equalizer, for example, place it close enough to the master control desk so that you can adjust the equalization without turning or getting up. If you're using a large number of hardware effects boxes, consider investing in a rack to hold them.
Position the microphone far enough away from the mixing desk that the singer can move comfortably around it. If your studio space is small, you may need to move the microphone into another room altogether. Use headphones to monitor the singer's levels when you're recording vocals, and turn down the monitors' volume to prevent feedback.
Connect any other instruments that you plan to use to the mixer or computer. If you're using a MIDI keyboard to control a synthesizer on the computer, for example, place it on a stand in a location in which the musician can comfortably play it.