Setup and Acoustics
Whether you’re going to record with a borrowed studio condenser, a road-weary old SM-58, or even something leftover from a busted karaoke machine, you should still be scouting your locations ahead of time, or at least quickly surveying any room that you intend to record in for the first time with an ear open for acoustic details. As you consider your subjects creature comforts in the recording space, also consider the quality of the acoustics, and try to pick a power outlet that isn't being shared by any heavy motors or refrigeration units. The spikes in the power levels caused by such motors will not only risk becoming audible in your signal, but can also wreak havoc on any digital processors and computer equipment.
Look around either the immediate or the adjoining space for a comfortable level of solitude for you and your subject, and which hopefully includes plenty of absorptive materials as well. When selecting your environment, try to find rooms with lots of drapes or curtains, and remember that carpet is great for soaking up reflected sound, as is plush furniture upholstery. Avoid getting too close to any large hard surfaces, especially if they are parallel or facing each other. Try to record at odd angles to such surfaces if you have no choice (avoid 90 or 180 degrees), and also be careful about microphones on tabletops since you can get noticeable phase cancellation effects depending on how you position or move the mic ( See: Microphone Techniques for Voice. While you decide on your mic placement and start laying your cable, try to keep eliminating potential environmental problems before recording to avoid nasty surprises during playback.
As you're laying any long cable runs, remember that signal flows out the male connectors and into female connectors, and that you should cross over any AC power cables with mic cable at right angles (90 degrees-not parallel) to avoid picking up any electromagnetic energy from the AC which can turn into audible signal via the reactance of the mic cable. Wiggle all cable connecters to check for any loose or intermittent connections, and either repair/replace, or if the problem is in the male end of the mic itself, at least coil the end of the cable into your grip to alleviate any strain on the connection itself, and then tape the relieving coil to the mic barrel, and tightly duct tape the wiggly connector to the barrel as well. You might also notice that the cable itself can introduce noise if it bumps or taps against solid surfaces. Without getting into the meanings of ‘self impedance’ and ‘leaking shields’, it should suffice to say that taping down your cable run, or at least eliminating movement is your first option.
So now put on the phones and actually listen to the room through your signal path if possible, or have someone test your mic placement while you monitor. Turn up the gain (initial volume) abit extra, and have a careful listen to the 'room tone' of your recording environment while noting and eliminating environmental noises (within reason). Remember that the sound of traffic or background music might sound cool, but later on they could make any edited sections sound choppy or abrupt. It’s better to record such ambiances separately and then loop them in later as separately mixxed tracks for maximum effect. Listen for any fans, AC units, or refrigerators that you can temporarily turn off. Can you throw a blanket over that PC during the recording if it has a noisy powersupply fan? Even fluorescent lights can introduce noise that you will hear later if you’re using a good microphone or high enough gain settings.