I'm very well aware that Rina-chan already made a detailed demo guide covering the basics, but the more tips the better right? I know this is so because I've been picking up these tips from a variety of professional voiceovers, especially my many mentors, and have found that everyone approaches demos differently. Not too surprising since times are constantly changing and demos aren't one-size-fits-all. That said, here are all those tips in one place and hopefully they'll give you a good enough idea to figure out what works for you~

After all, demos are meant to make YOU look good and hired/cast/whatever, not have you blend in with the others, so feel free to “break rules” so long as it works in YOUR favor!

(Expect more information as more tips come in.)

By The Numbers:


• Recommended Total Runtime: 1-1.5 minutes
  
  It used to be as long as 2 minutes several years ago, but times have changed as the digital era created people with shorter attention spans. Keep it short. 1 minute alone should be enough.
  
  
• Estimated Time Per Voice: 6-8 seconds
  
  The length of 6-8 seconds is roughly around 1-2-ish sentences, which should be enough time to develop a character. With your better voices, try to have them be longer than your weaker voices.
  
  
• Estimated Number of Voices: 7-10 unique voices
  
  While deciding on what 7-10 unique voices to use, it's advised to have around 10-15 different clips to choose from. That way, you aren't limited to what you recorded and you can have an easier time determining which are your best performances and which clips are weak or too similar to the others in order to not include them. Not only that, but you may be able to sneak in more voices if you're satisfied with the voices you have.

The Demo Itself:


• What to Voice
  
  Plan your demo reel around the voices you have at your disposal, like listing which voices you can do before doing it. Try having both extremes of your range so listeners can assume that you can do everything in between, which is handy if you can't fit everything you can do in your demo. Unique voices can be different parts of your range, accents that you're good at, textures you're comfortable with, or even simply just different characters. It's hard to describe the last one, but basically, it's possible to get away with using the same voice several times if you're capable of conveying a different character for each instance. There are professionals who have limited vocal range, but their versatile acting makes up for it. For instance, a sweet girl with a high voice is much different from an evil, demon-possessed monster with a high voice. Mix things up and combine these to make the possibilities seem endless, even though you don't necessarily have to make it so.
  
  
• What to Say
  
  Plan ahead what you're going to say. Slating your name in your natural voice isn't a must, but it doesn't hurt since people get to know what you really sound like. Random, thoughtless chatter is discouraged. A majority of the time, theme reels don't work because they reveal how poorly planned or written it is and that always exudes amateur. In example, demo reels about a bunch of voices in a house talking to one another can come off as distracting and even annoying to most. Voice work comes in all kinds of forms, but you have to admit that almost all of it requires acting of some kind. A character demo, which works for animation and video games, requires character acting while a commercial demo requires a different kind of acting. Try to have all kinds of material at your disposal to work with, like snippets from scripts, magazines, graphic novels, and pretty much anything that can concisely convey the character behind the voice, because there is less risk in presenting something badly written. Avoid offensive material, like discomforting dirty jokes.
  
  
• The Order
  
  Have your strongest, best voices play first (first 10-25 seconds). Demos are all about first impressions since people tend to listen to these one after another and are very likely to not listen to the entire thing if you don't keep their interest. Try to vary up the voices so they don't run together and sound too similar, like having a dramatic character follow an energetic character instead of two consecutive energetic characters. Ideally, you'd like the listener to get into the state of “Oh, I'll listen to just one more... This one sounds neat, I'll listen to this one too...” until they finish the reel and even then want to hear more. Some people who know how to sing feature a snippet of their ability at the very end.
  
  
• How It'll Sound
  
  Ideally, demo reels feature stuff you've done, like characters you've been. That's why most demos are mixed to include background music, sound effects, and other extra things to seem like it was taken directly from a show or movie. Producing a demo is usually expensive because you need a professional studio, someone skilled mixing the demo, and to pay for any copyrighted music you may be using. However, there are effective demos with no music or sound effects whatsoever so the listener can pay more attention to the voice instead of being distracted by the extra bells and whistles. Ultimately, it depends on what you can do, since voices in a vacuum don't always sound that good.

Presentation:


• The Cover
  
  Have your name on it and it never hurts to have your contact information on it as well. Try to avoid something tacky or overdone like a microphone as a graphic on the cover. Try to have something visually appealing and appropriate, like an animated, cartoon-ish picture of yourself on the cover it's a character demo.
  
  
• Packaging
  
  Go for the standard jewel case instead of the thin jewel case. While the thin jewel case is more compact and “modern”, the standard jewel case makes it possible for people to see your name on your demo reel from the case's spine should it be in a stack of CD's on a busy person's desk.
  
  
• Delivery
  
  Ideally, you'd want to hand your demo directly to people who would be interested in hearing what you have. It's not uncommon for professionals to have around 10 copies with them at all times to hand out so people can remember the face behind the voice. However, it is HEAVILY discouraged to be pushy while giving people demos. You need to have good gut instincts to know the right time to give a demo to casting directors and such or you'll run the risk of never being listened to. Be professional, not desperate. Show them that you want to work with them, instead of rushing by, shoving your demo into their face, and coming off as someone who thinks they'll take anything like that. In the event you cannot distribute your demo in person (or if you run out of copies even), have your demo(s) on your website.