Back in 1987 I wrote a play called 'Kenny' about a teenager running off from his Children's Home. I left it in a drawer but in 1990 sent a copy to Radio 4 producer Richard Wortley. He loved the play and it was broadcast as part of the 1991 Young Playwright's Festival. A Literary Agent heard the play and signed me up. A lucky break.I went on to have 'Stranger In The Home' broadcast in 1993, then to write playscripts for books. My Radio writing was a while ago but some things still hold true.
Find yourself a contact.
Scour the Net and get the name of a Radio Producer to stand a better chance of your work being read. Find out what sort of stories he or she favours. I used to send a polite note asking to submit some work but you could probably just send something straight off. It'll be read, eventually, by a paid script reader and if liked then passed on to the producer. Nothing is ever easy for writers
Be clear about the story/message you want to get across.
Drop the listener into a dramatic part of your story. Get them hooked in the first few lines. Write from experience to get the truth across. If you don't have a good grasp of your story then your audience won't either.
Write with a flow.
Your scenes can be short or long but they must carry the listener with them. I feel that Radio is very filmic - anything can happen - and the limit is your imagination. A good use of sound effects will break up the story and give everyone a sense of place and being there. Less is more.
Make your characters individuals.
They will need their own voices, ages, origins and vocabulary that actors can play with. And it helps to hint at or refer to incidents in their pasts. Make sure they have clear goals to reach (or miss) and a strong motivation. Btw, it helps to give characters names that start with different letters.
Make every word count.
There can be no room for fluff. The story has to be pacy and challenge the listener to stay along for the ride. Each sentence must mean something dramatically and drive the narrative.
Use some Music.
Choose music that really stirs you and gets the mood of the play across. Modern or classical, you decide.
Enjoy the silence.
Use silence to change a scene, suggest high emotions or tension in the air. It's not 'dead' airtime but something as important as words or sound effects.
To see how newer plays are set out check out the BBC Writers Room info.
To see how I set out my play 'Kenny' click on this script thumbnail. It shows my cutting & scribbling out during the BBC studio recording.