Choose scriptwriting software or a template for your word processor that automatically and correctly formats your radio script as you write. Movie Magic Screenwriter is expensive, but it has templates for radio scripts. Powerwriting offers a Microsoft Word template that automatically formats your radio scripts. It isn't necessary to use one of these programs, but either of them will take the headache away from the formatting end of writing scripts for radio commercials.
Spell out words you believe the announcer will have a hard time pronouncing or might pronounce incorrectly. Numbers should also be spelled out. Use a double dash when you want the announcer to pause. Radio scripts are typically written in two columns, with sound effects on the left and what the announcer will say on the right. Abbreviate announcer as ANNCR and sound effects as SFX. Column one is where you write either ANNCR or SFX. Place any speech or dialogue in the second column, as well as the sound effects. Be sure to capitalize and underline the sound effects.
Get to know the company you're doing a commercial for. Learn all you can about the company's product or service. Consider the target audience for the product or service. This is the first step to creating an effective commercial that will help sell. Find a hook to use right up front--something that will grab the attention of the radio audience you're targeting. Think of the sound of an automobile accident and the radio announcer asking, "When is the last time you checked your brakes?" It's bound to catch your attention. Another popular hook idea is to use a few notes of a catchy song before the reading begins.
A typical 30 second radio spot has between 80 and 100 words. Use concise, vivid, active language and get to the point. Shorten phrases. Don't write something like "due to the fact" when you can write the word "because." Use direct verbs when you can. Instead of writing "you will save," simply use the word "save."
Always write your radio ad copy in present tense. It brings your listeners into the moment.
Take advantage of sound effects that will enhance your commercial message without distracting listeners. Sound effects can, when used properly, enhance the presentation of a radio spot, since radio is aural. The sound effects used depend upon the commercial and the product you're selling. The sound of a can of soda opening and being poured into a glass in the background while the announcer talks about the refreshing taste of "such and such" beverage is an example of effective sound effect usage.