(Are you a good waiter)

Often, someone has an excellent idea in their head but doesn't know exactly how to start writing a book, as they have difficulty materializing the thoughts to turn them into good content. Thus, the first line or the first paragraph of a work can take years to be written. Starting a narrative with the famous “Once upon a time…” might work, but depending on the genre, it won't be enough. So what steps can the writer take to start writing? {Because I'm back to writing}, I'll try to answer some questions.