These are some points which you can keep in mind while writing a story-
* Always before starting to write a story have a clear picture of what the story will be like. You should always write the outline of a story before writing the actual story. Don't forget to give your story a catchy title.
*Try to involve your reader emotionally in your story. For this you can use any emotion like love, hate, fear but make sure you have at least one of these emotions.
* Don't try to deviate from the plot
* Try to involve all the five senses of the reader. How did the surroundings of the kidnapper's house look? How did the dead body smell? What was the look on th dead body's face? What kind of wound killed him? etc. These kind of details add more effect to the story.
* Always look at your story from a reader's perspective and think what should I write that would make the reader more involved in the story. Then write that. But also beware of giving too much details as they tend to slow down the story.