When I first started my novel, I thought the keys to a good thriller were plotting and pace. Since both of these are my strong points, I felt I was set. I wrote the first scene and immediately realized I was wrong.
The scene had action and dialogue, a murder, a twist, but still, it felt dry and skeletal. In reading it over, I began to understand that the least interesting thing about a book is what the characters do. Why they do what they do is much more intriguing, and more fascinating still is how they are feeling when they do it.