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.
Also listen for sibilance. Strong 'ess' sounds are best corrected at source, by using good mic technique, but sometimes they're unavoidable. If you hear an 'ess' that really sizzles in your recording, you can manually reduce its volume. You can, of course, also use a de‑esser, but do be careful, as applying some de‑essers to the entire audio file can alter the sound of your recording. It often works best to apply them to short sections, either offline or using automation. My preferred de‑esser plug‑in is the one sold by Eiosis (www.eiosis.com),Make sure you record some silence at the end of each take. That way, if a great performance suffers from noise issues, you have something to feed your noise‑reduction processors. Just don't rely on this technique too much! which cleverly separates the esses from the rest of the audio and allows you to manipulate them independently. If you want to learn about some more advanced strategies for de‑essing check out Mike Senior's article from SOS May 2009 (/sos/may09/articles/deessing.htm).
Always update yourself on industry standard rates. I recommend reviewing the union rates set forth by SAG-AFTRA. Voices.com also offers a rate card as well Voice-Over Resource Guide. Upon viewing these rates you may find, based on your current experience, you fall a little lower or higher than said rates. Maybe you have a great deal of experience in the commercial voice-over world, but now you’re branching out into narration, e-learning or audiobooks, so your voice-over rates may be a bit lower for that genre as you find your footing. The most important thing is that you have a baseline rate for yourself and you’re comfortable and confident stating this rate to a client. It’s beneficial to first ask your client’s budget and proceed from there. While stating your rate, also take into consideration edits and pick-ups. It’s customary to include one free round of edits in your rate, but any edits or pick-ups past that incur a fee.