Today, we'll talk a bit about tone. Think about your story. What kind of mood are you trying to evoke? Are you going for humour, or a creeping sense of dread, maybe? Is it the right choice for the story?
Sometimes a story fails and you have trouble pinpointing the cause. The plot works, the structure is solid, the characters are interesting; so what's the problem? It could have something to do with tone. Maybe the tone is all wrong. A horror story doesn't feel frightening, for example, or maybe the tone is inconsistent: your story starts off as horror and degenerates into slapstick halfway through. There's nothing wrong with the combination of horror and humour, but you should start as you mean to finish, or the reader will feel confused.
Ambiance is important. You build it with word choice, your use of setting, the way the characters react and how their mood colours their observations, character voice. Tone should support that.
One way to practice this is to write a scene using several different tones.
After all, sometimes it's not what you say, it's how you say it.