If you choose to write a narrative, it should be a story in which either you or someone you know well was actually involved. You should avoid stories that simply recount accidents. What I mean is this: a good story needs to have the element of choice in it. If you describe an accident, you need to show that decisions led up to it. This story should be about people, about the decisions they make and the consequences that follow.
A narrative is a moving picture. Like description, narratives need to have a rich texture of details so that the reader is seeing, hearing, smelling, and touching. The reader should experience the story, not simply hear it.
Stories add the element of time to description. Often stories start at the beginning and then follow the sequence of events chronologically. However, an effective variation on this pattern is to start in the middle of things and then use flashbacks to fill in the background information. This method is especailly effective in holding the reader's attention.
There are two extremes you want to avoid in writing a narrative. First, you can simply tell the story, event by event, without giving it any texture because you leave out descriptive details and dialogue. At the opposite extreme is a narrative that attempts to tell everything, painting detailed descriptions of every scene, quoting everything that is said, even speculating about the thoughts of the characters. A good narrative has texture, but it is suggestive rather than exhaustive. After all, the reader's imagination needs some room to fill in details. Giving too many details not only overwhelms the reader's imagination, it also slows the pace of the narrative.
Pacing is an important concept in narrative writing. Basically, pacing means that the writer sometimes slows the pace by putting more detail in, but sometimes she also hurries over details. A good way to know where to put in details