I like that you asked about books people buy because writing a book that sells is a whole different animal from writing a book for your own enjoyment:
- Read the best books in the genre you wish to write in.
- Choose a best-selling book in that genre and take it apart. How is it structured? How long are most books in that genre? How many characters (if it’s fiction) are there and how are they described? How much description is in the book? How fast does the story move? Everything you can think of.
- Learn the craft of writing. Yes, writing is a craft and any craft can be learned. Buy a book, take a class, go to a workshop. Or all of those and more but make sure they teach you about your chosen genre because one genre can be totally opposite a different one.
- While you are learning, compare what you are learning to what you figured out when you took that book apart. The lessons you are taking will tell you the ‘why’ of what you’ve already figured out about your chosen genre and that will help you know how to write your own book.
- Then write your best-seller.