Be mindful of the sounds of your heating and cooling system (this goes for a home recording studio, as well). If you can’t find a spot where you can’t hear air rushing through your ducts, you may want to shut down your furnace or AC for the duration of your recording. If your recording space is near a window, listen for sounds of traffic — especially loud trucks. They will definitely show up in your recording.
As the engineer, your key job is to select and set up the recording space, choose and position the microphone, set levels and make sure you're recording a good, clean signal at a healthy level. Like music, the louder the signal you want to record, the less audible the noise floor, but you don't want to have to speak louder than sounds natural, and you don't want to overcook things when tracking: any distortion will be very noticeable on an exposed voice part, and an otherwise great take with digital clipping won't be acceptable. If you notice clipping only when you start editing, software clip restoration tools might help to make the take usable, but it's not going to be perfect. Remember that although you may have needed to record 'hot' on analogue tape and older 16‑bit digital recording systems, modern 24‑bit A‑D converters can accommodate a much wider dynamic range, so you no longer have to track so loud: you can leave much more headroom.
In other words, Mirek gave us all the information we needed to start the job. Unfortunately, though, that's not how it usually works! Usually, you'll need to work hard to get all the information you need from your client to do the job well. If you're at all uncertain about their expectations, whether about the performance, or about technical and organisational issues such as file formats or payment procedures, save yourself time and a headache by clearing up all doubts beforehand, and don't hit the record button until your client has given you the green light by email. With that sorted, you can more easily don your other hats and get on with the job.
When asked by someone outside of the industry how much I’m compensated for a commercial voice-over, I can see their eyes grow large with excitement. It may sound like a large number for two or three hours of studio time, but what is not understood is the investment in time, money and education that it takes to begin and sustain a voice acting career. As voice-over professionals, we need to remember (especially if we are setting our own rates) that the time we have spent in classes, coaching sessions, and our booth add up to our expertise in this field. When setting your own voice-over rates, or negotiating those set by producers and/or clients, you need to not only consider your session fee (the time spent in the booth recording the specific copy), but also all the training you’ve acquired and the investment in your home studio (which helps make your client’s job much easier).