A demo recording of you doing voice-over work is your CV and your business card combined. If you're applying for a voice-over job, you can send the potential customer your demo via the Internet. Ideally you have multiple demos for different types of gigs. For commercials, clients want to hear 60 to 90 seconds of voice work. If you're auditioning as an audiobook reader, five minutes of demo proves that you can stay in character over a longer stretch of time.
Both union and non-union have advantages and disadvantages; ultimately, it’s a decision that you, as a voice over actor, will have to make. Like everything else, it’s of critical importance that you do your research and weigh up the pros and cons. Seasoned pros will usually tell you it’s best to be a union member because, if you run into trouble, the union will fight your cause.
I use the Adobe Audition package to edit my own voiceover work, but the techniques described below can be used in most audio‑editing software. Start by saving a new version of your original recording. (I keep the name of the file the same, but change the extension from _original to _edit.) Next, I'll turn my attention to the end of the recording, where I stepped away from the mic after the second take and recorded about 10 seconds of silence. Although processing is usually kept to a minimum, dealing with sibilance is important, and Eiosis' De‑esser plug‑in is much more precise than most.Wearing headphones, I can zoom in on this 'silence', turn up the volume, and listen for any background noise. If I notice any constant noise seeping into the recording, I may consider using Adobe Audition's noise‑reduction tool to capture a one‑ or two‑second profile of the silence, and then reduce the offending noise by about 75 percent throughout the recording. I should stress that this is rarely needed, and it's always a last resort, because such processing can generate swirly, metallic artifacts that draw more attention to themselves than the noise you intended to eliminate! But it's good to listen for such issues with fresh ears at the start of your editing session. If you find yourself using noise‑reduction often, that's a sign that you should find a better place to record, or improve the isolation of the space you've chosen. Don't forget that there are other ways to deal with some noise: often, a high‑pass filter is all you will need to clean up a recording, for example. Also remember that if your recording is to be mixed with music, slight background noise won't be noticeable, and that the more exposed your voice in the end product, the more problematic noise will become.
Next, run these files through any standard EQ high‑pass and low‑pass filters you use, zoom in on the waveform, and select a one‑second strip of silence from each recording. Save these strips as separate files. For instance, on my system, a one‑second strip of silence recorded at 16‑bit, 44.1kHz on a Neumann TLM103 would have this name: room_tone_neumann_tlm_103_44100_16_one_second.wav. Ideally, the noise floor of each strip will be lower than ‑60dB. Now, when you have to remove a bump or a squeak between words, you can paste in a piece of these strips instead of muting, which would draw attention to the edit.
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.

Even if you're mixing yourself, it's better to add EQ and compression only when you can hear how it will sit with the soundtrack or special effects. Ultimately, it comes down to knowing what your voice will be used for and making a judgement. For instance, if I'm recording a tagline for a TV or radio advert, I'll generally run a mic into a nice preamp (where I might add slight tube warmth, and subtle EQ or compression, just to give the recording a bit of 'body'), and I may do a little de‑essing using a plug‑in when performing any edits. However, for e‑learning jobs, corporate videos and so on, I'll tend not to add any creative processing while recording or editing, and will only use the de‑esser ever so slightly.
"When recording voiceovers at home, you have to focus on performance: keep your energy levels up, stay true to the page, pronounce words correctly and consistently, and make sure you keep to a schedule to make the deadline. Prep well so you don't waste time second‑guessing yourself, looking up words as you go, and remember to not over‑ or under‑direct yourself. Also, make sure you know your recording equipment and room well; being able to quickly make adjustments to mic placement, levels, and so on, will make you more efficient.”