Choose any idea, even one of the crappy ones. Now’s not the time for self-doubt! You know you can make it better! Pick at it, polish it, make it shorter. Take out unnecessary words and sentences. Add action. Add drama. Add humor. Agonizing over finding the perfect idea is exactly what leads to writer’s block. You have to realize that it won’t be the perfect idea until you do the work.
Imagine what pictures might go with your words. If it helps you to visualize the final product, make a little dummy book. That will at least help you to see how the flow feels. DO NOT send this dummy book to the publisher -- this is for your eyes only! You can show it to your family or a group of kindergartners, but NO PUBLISHERS!
You can add details and flavor to your book on every page. Use your everyday life to find original ideas. Polish your sentences until they read in a rhythm. Did I say rhyme??? NO. Rhythm. You just want it to read with a nice flow. Read it out loud and see how it sounds. Have someone else read it to you. Rewrite it over and over again until it’s just they way you hoped it would be.