Voice refers to the mood the writer conveys through his writing. Evaluating a writer's voice involves paying attention to word choice, sentence structure, humor or lack thereof, simplicity or complexity of descriptions and other components that make up how the story is told. The writer should use a voice appropriate to the content of the narrative. For example, if the story is light and funny, then the writer could use simple vocabulary and a joking tone.
Another major element to a successful narrative is character development. The people in the narrative are referred to as the characters, and a well-developed narrative will offer unique, realistic, and well-described characters. The writer is usually the main character and narrator, since it is a story about the writer herself. Because the narrative should show some kind of change or decision for the main character, the writer must convey that change in order to successfully develop the main character.
The plot of a narrative is also essential to consider when evaluating the narrative. The plot should follow the traditional plot arc, which starts with introduction, then gives rising action, which leads to the climax -- the point at which things change -- and then the falling action and conclusion. Of course, many ways exist to build the plot -- and experienced writers might take liberties with its structure -- but the plot should move forward, building toward a major climax.
Finally, theme comes into play when evaluating a narrative. A successful narrative will not only offer good characters, plot and voice, but will have a theme to which the reader can relate. A theme is an overarching concept that the narrative explores. Some examples of themes include, "knowing yourself," or "family ties" or "loyalty to friends." In a good narrative, the theme comes through a specific person's story, but could be relatable to a number of people and relationships.