Think about your theme. Then, write lines that reflect it in different, shorter ways, double-spaced on a page. When the page is full, delete all the lines you hate. Pick the best line from that batch and start over. Write another page, then delete the lines you hate. Only keep the lines you don’t hate. Pick the best one and start the process again. Over and over again. Go where the words lead you.
Eventually, you’ll have a half dozen lines that might be okay.
Now, you have a set of possibilities to present to the client. Ask the clients to delete the ones they hate.
The one left alive is the winner. Until legal nixes it.
Then you start all over again.