COVERING LETTER - PERFECTION REQUIRED

(It's a long one - settle down with wine, chocolate, anything you need. But there is a competition at the end, so it will be worth it.)"What's so important about the covering letter / query letter? After all, isn't it the book that counts?"Yeah, sure it's the book that counts. But the agent/editor isn't going to get that far if your covering letter isn't good. No, forget that. The agent /editor