Identify the object of your metaphor. Select the word that is important to your overall story. Consider a love story where you are writing a male character who no longer believes in love, an idea that you could write simply but would leave your reader uncertain as to why he no longer believes or if his mind could be changed. You could select his heart as the object of your metaphor, knowing that you can use it to explain his feelings more deeply, and turn it into a ship.
Use imagery to construct a comparison that explains, exemplifies or contrasts with purpose, the nature of your metaphor. Select your words carefully to avoid reader confusion and make sure that your metaphor says what you intend. For instance, our man who no longer believes in love can become a ship lost at sea. This imagery suggests that he once believed in love but something happened, possibly a broken heart.
Build on your metaphor by adding specific elements that help you establish a dual purpose or second meaning. Add elements to your metaphor that are specific to the object you are changing. As an example, your ship lost at sea can become a ship lost at sea, without a flag. Your metaphor has taken on a new meaning with the addition of the flag and now your male character has become someone who may have lost his ability to love because he doesn’t have a place in the world where he really fits in.
Add other elements of your story or other characters to your metaphor, while keeping to the theme of your story and the meaning of your metaphor. Select another element or character and consider how their relationship to your male character can be described with the same metaphor. For instance, a powerful female character who is determined to make him love her could change your metaphor to read, “he is a ship lost at sea, without a flag, and she the bold privateer rushing to his rescue.”