The Three Big Ones
Plot, Characters, and Atmosphere
The sandwich of writing. I may or may not have been hungry when writing this.
Let's take a step back for a moment. Before you go creating an elaborate world with your dozen languages, ten thousand year history, and parrots ruling the kingdoms from thrones of magical xerysth, you may want to rein it in and consider how your world fits into the story. Sounds crazy, but the world is as much a part of the story as the story is of the world. So before getting too far, consider the three spheres of a story: plot, characters, and atmosphere.
Plot is the bread of the book's sandwich. It gives it body and sustenance and without it, you're left with something that's not really a sandwich, or a book. You're left with only a pretty cover and your smiling face on the back. So what is plot? It is simply, the main events of a play, novel, movie, or similar work, devised and presented by the writer as an interrelated sequence. In another way - action of character/environment causes A, leads to B, results in C. Plot is fundamental to a book and is essentially the "story" itself. Plots can easily be lacking, resulting in cliches (avoid them if it all possible, link at bottom of page), weak emotional investment, and ultimately the loss of readers.
Therefore, focus on plot, your "story". Read authors that you enjoy to get a feel for how they successfully manage their plots and keep you hooked through each page. Perhaps you can also structure your plot after the popular and proven story arc (link below). Ensure "sparks" (major character/plot altering events) throughout the plot, typically every one hundred pages or so.
http://www.dailywritingtips.com/how-to-structure-a-story-the-eight-point-arc/
Story Arc
Second, are characters. They are the meat of the writing sandwich. Without them, you're left with a sad flop of bread, and if you're lucky, some cheese. Characters are the center of the story, critical to the success of any book. This should go without saying, so ensure that main characters are well-developed (that they are described well, have a thorough background, and engagin plot). Do not have main characters along for the ride. Every character should have a purpose! The same should go with secondary characters (characters whose roles are not focused on in the plot).
A character's purpose should never be simply to add word count, even secondary characters can have goals! Try and mix up a variety of characters, dynamic (character is different at end of story than when he/she was introduced) and static (character remains the same through story). No one remains the same forever, and neither should they in a book! Also, be sure to avoid cliches!
Jamie Lannister, Game of Thrones
Lastly, but truly no less important, is the atmosphere. Atmosphere is the cheese, veggies, and that awesome chipotle sauce on top (I swear, I'm not hungry!). I have touched on this topic briefly in my last post (World Crafting), but I will discuss it again. The atmosphere of the story, or its world, is vital for a reader to stay connected and engaged with the book. The book can be the most elegantly worded and the plot can be revolutionary, but if the reader cannot make the world "come alive" in their heads, then many will put the book down.
Ensure that your world is truly a world, that it has its own cultures and people, that they live and work and fight and love. Build a world of emerald pines and jutting mountains, or a world of gray skyscrapers from blue to blue. Create your world and then share it with your readers, making sure they can feel everything that you feel and see everything that you see. Only then, will you have a world worth sharing.
Thanks as always for reading! More great links below!
Map of Tarsha, The Atonement Trilogy, Bryan Gifford