The world's best opportunity is pretty easy to come by. All you have to do is become president of the United States. Do that, and your new children's book will be published by Random House; enjoy a first print run of half a million copies; garner as much media attention as it can handle; and rake in the cash (in this case, I'm glad to report, the cash will be donated to a scholarship fund for children of disabled war veterans).
So if you're struggling for book publicity opportunities, you know now what you have to do to garner those media interviews and book reviews. Become president of the United States, and book promotion opportunities will follow.