Any aspiring novelist would do well to read How Not to Write a Novel by Howard Mittelmark and Sandra Newman. The book includes 200 mistakes to avoid if you want to write a novel that people will want to read. It focuses on mainstream, commercial fiction, but most of the rules apply whatever the genre of novel you want to write.
Starting with Plot and covering character, style and creating a fictional world, the book shares great advice and extracts from imaginary bad novels to give the reader a very clear idea of what doesn't work in a novel.
I have to admit I disagreed with their prohibition of animals in novels. Their point of view seems to be a pet should only be mentioned in passing and then basically ignored. Obviously badly done, a pet can become an over sentimental indulgence in a novel, but, if done well a pet can become a significant character in a novel and can really add to the reader's understanding and empathy for the human characters. I've read many novels with good pet characters (the best being Elsa Morante's amazing novel History, which I reviewed here.)
Apart from that though, great advice and it's very entertaining too. I found myself having to stifle my laughter more than once while reading this on the bus.
How Not to Write a Novel by Howard Mittelmark and Sandra Newman published by Penguin