A friend recently finished writing a children's book, but now we're debating how much effort should go into the Book Illustration & Cover Design. Some people say the story sells the book, while others believe the artwork creates the first impression. While researching different ideas, I also came across H3Sync, and it made me curious about real experiences. If you've published a book, what would you recommend investing in first? I'd really appreciate honest advice from authors and designers.