How to know what makes a good voice reel
A solid voice-reel all depends on the type of voice work you would like to get involved with.
There are jobs available in a variety of mediums; Adverts, Video Games, Animation, Narration, Radio and Audio Books. It is important that you really specify what you want to work in.
Most good voice-reels are divided into sub categories - this makes it easier for a casting director to select what they need for their project.
A good example of voice-reel division may be:
Adverts and Narration
Video Games & Animation
Radio & Audio Books
A voice-reel should never be too long, if you divide your reels you should never be looking at any longer than 2 minutes. A casting director would've heard what they wanted to hear very quickly.
For Adverts and Narrations - pick material that suits your vocal quality, stick to your strengths. If you have an energetic, youthful quality it might be a better idea to stick to adverts for children as opposed to sophisticated wines.
If you are interested in Video Games and Animations - have a good think about "the voices" you are good at, those characters actors develop from childhood. Really get specific with the engaging and colourful characters you have stored in your voice and present them in short and snappy moments. This reel should be big and have a mixture of humour and excitement.
With Radio & Audio Books, find monologues and pieces from novel that fit your vocal quality. The monologues should be engaging and are better in the present tense. Give us an example of your natural voice and potentially a particular accent you are really confident with. Picking a section from an audio book can be tricky, but try to find an author who has a similar tone to you - it might be his or her characters are similar to you.
The important thing is engage your listener, treat it like a audio performance as opposed to an audition. Don't stretch yourself; any examples of you pushing will be highlighted on a voice-reel.