A lot of people that give writing advice focus on the plot. What is it? Is it strong? How many points and arcs does it have? Basically, what is the progression of your story? Many make it out like plot is the most important thing to focus on when writing your short story or novel. I, however, disagree.
While plot is still important and definitely in the top 5 things to keep in mind when writing, I believe the number 1 focus should be on characters and their development. Think about when you are reading a novel. What makes you connect to the story? What makes you want to read more, even when you have to put it down to do something else? What The characters. Through believable characters, the readers make a new friend (or, in some cases, a new enemy) that they are passionate about and can relate to in some way or another. Watching the character change and grow is one of the biggest draws a novel can have.
Many writers are guilty of developing a great character in the first few chapters, then turning away to focus on the actions themselves. While there still needs to be movement and adventure in the plot, it can't take over your story. People don't relate to events; they relate to emotions, thoughts, and personal actions. Through triumphs, trials, and failures, your audience becomes hooked on your character. Therefore, this is where you need to channel most of your energy.