Radio advertising has always been a challenge for many, as it is deemed difficult and challenging. Most of the people on planet earth are visual people (up to 70%), as in they can visualize things better than hearing them. This is an obstacle, but also an opportunity.
The keyword is visualize. Create vivid descriptions that make the audience visualize pictures and images in their mind. You have to give more details on the picture you want them to have. E.g. at 1 am in the morning, I woke up to a cold night of 1 degrees C. I went trekking over a rough, jagged, and craggy terrain, which was enveloped by dark sky, adorned by many bright stars.
Use sound effects and vocal variety to enhance the message better. Go soft or loud, stretch certain words, and vary the tempo. You will create very vivid pictures in your consumers’ minds.
One final advice I have is to not have the perception that TV is the same as radio advertising. You cannot use similar or identical format towards both media. Each requires its very own treatment. The worst kind is just to port over the TV ad to a radio ad, without the visuals. What you can do is to have similar messages for both media, but vary the format and treatment.