Complete an outline of your story. Although not all writers start a story by writing an outline, it is a good idea to help keep you on track and ensure you don't leave out any important information. Outline your main characters (including the antagonist) and their motivations. Note the main events and conflicts. Explain how these conflicts will be resolved.Consider point of view, or from what perspective your story will be told. If you are artistically inclined you can sketch out the main characters, events and a rough plot on paper.
Introduce the main character in the beginning. Set the mood and the scene using rich description. It is essential that your first sentence engages the reader and gives him the motivation to continue reading your story. The beginning can also include other characters, although try not to introduce too many early on so as to not confuse your reader. Show the reader, don't tell them what is happening.
Write the climax,or turning point of your story. This is the middle of the story, and is the point at which your main character encounters a serious problem or obstacle that needs to be overcome or resolved in the conclusion. Make this problem a surprise to the reader and one that is difficult to solve. A good idea is to create a twist your reader didn't see coming.
Tie up all of the loose ends in the end, and answer the questions raised in the beginning and middle. By the end of the story, your main character should be changed or develop in some way.
The last sentence in your story is just as important as your first. Make it satisfying and thought-provoking, and your readers will carry the story with them long after they've finished reading it.