Videos come in all shapes and sizes. Some happen to be exactly 30 seconds long and formatted for a television screen. Occasionally these 30-second videos have voiceovers. Here are some things to keep in mind when you write them.
Write both sides of the script: TV scripts are written with visual instructions on the lefthand side of the page and the dialogue, voiceover or music direction on the right. Write that way from the start. Both sides. Simultaneously. It'll prevent you from writing your voiceover as a paragraph of body copy. And it'll get you thinking about how sight and sound can complement each other, allowing you to communicate more in less time. Screenplay format is ok, too. But it drives me crazy when I see a voiceover laid out like it's a chunk of copy.
Cast before you write: Pick a favorite actor. Someone with a distinct vocal pattern. (Morgan Freeman, Matthew McConaughey, Cameron Diaz, Edward Norton and Kris Kristofferson have all been inspirational for me. Al Pacino might be too unique.) Then write your voiceover. Let the actor's voice echo in your head as you write. This exercise will make sure your script is written to be heard instead of read. And it'll make your tone cohesive and interesting.
Transcribe other people's scripts: I was told that as a boy, David Mamet recorded his parents' dinner conversations and then transcribed them so he could see the way everyday conversation looked on a page. It's a mess. People interrupt each other, repeat themselves, and never speak in complete sentences. Try it. If you don't feel like eavesdropping on a conversation, go find your favorite spot on YouTube and transcribe it. You'll be amazed how sparse and odd it looks.
Read your voiceover out loud: Act it out. Don't just mutter it to yourself under your breath while staring at your monitor. Read it boldly. This will ensure your flow is perfect. And it will also ensure that on recording day, you have a clear idea of how the talent should read your script.
Read books: Two of the most famous spots of all time, Surfer and America, have voiceovers derived from literature. More than radio, more than copy, more than headlines or websites, a voiceover is a copywriter's chance to dream big. To write something that will make people's lives better. Go do it.
[Update: Thanks to the Egotist network, this piece has found a home in Denver, Minneapolis, Des Moines, Toledo, Detroit, Los Angeles, Alberta, San Francisco, Atlanta, and DC and Baltimore.]