Apparently, Christopher Lee used to read The Lord of the Rings once a year. This was a habit he began decades before playing Saruman. He isn't alone. Many people have a favourite book that they read over and over, without it ever becoming stale. If you ask me, the definition of being a successful author is writing something that people not only remember, but enjoy re-reading. Strange as it may seem, not every novel on the bestseller lists has that quality. What is it that keeps readers coming back?
    Important as plot is, it isn't likely to make readers return to a novel, although it might interest them in the next one by the same author. Novels such as thrillers and whodunnits rely on fast-paced, edge-of-the-seat, suspenseful stories with unexpected twists and surprise endings. However, once you've read them, the surprise is gone. If that's all they have no-one's going to give them a second look.
    Beautiful language is a plus, providing it moves the story along and doesn't bring it to a standstill. Depth is another thing that can encourage a second reading–subtext or complex style that reveals more details each time you read it–but here again, writers are likely to deter readers from picking up the novel in the first place if they get the balance wrong.
    The one thing you can rely on to drive all else and bring readers back a second time (or to sequels) is engaging characters. It's Poirot's idiosyncrasies that draw readers back, even though they already know who the murderer is. It's the relationships between the members of the Fellowship that make the characters in The Lord of the Rings live on in readers' imaginations.
    Before you begin to write your novel, get to know your characters. What are their back stories? Do you know where they came from, what they like to eat? How do they react to trouble? Can you hear how they talk? The more you know about your characters, the fuller they'll be and the more likely it is that readers will identify with them.
    One word of warning: you can plan a plot, you can create poetic language, but characters will always try to take control and head off in their own direction. Following them can take your novel to interesting places, but they might also lead you down the garden path.