I have started many novels only to leave them unfinished. Most of these novels began with a germination of an idea that grew and then withered on the vine. Some, just weren't meant to be, really. As I was sifting through this veritable graveyard of manuscripts one day, I noticed that many of the "best" discarded stories had some sort of outline attached to the file.
The point is, it seems, that outlines provide more direction. I have always felt a little confined when I use outlines too ardently. However, I have noticed that the best outlines leave flexibility to the characters and the plot to grow and move within the confines of the outline. Plus, it is always good to be reminded that the outline isn't chiseled into stone like the Ten Commandments.
Every writer has a method to writing outlines. My most successful attempts at outlining have been to create "chapter outlines" with general plot queues. This allows the novel to retain a structure, stay true to the "story" but allow for the creative juices to infuse the narration.
See, writing a novel tends to tax two sides of our soul. First, we always credit the "Muse" for the creation, the creativity of our imaginations. But, for a novel to speak clearly, we must tap that other, more logical side of our soul so that the story is not only imaginative, creative and artful, but also meaningful, clear and realistic. It must have structure, it must have clear sentences, it must have likeable characters, believable dialogue and gripping conflict. The outline is one part of the craft of writing.
So, how do we marry the craft of writing an outline with the art of telling the story? Whatever form your outline takes, it must give your story a backbone. It is your "Muse" that will form around that skeleton and breathe life into the bones. Without the outline, it is possible that your story will seem amorphous or without a skeleton, being all blood and guts, skin and sinew. But, with a concientious attempt to provide structure through an outline, your story can stand on its own and seem more solid.
For practice, try using a short outline form for a short story or play. Focus on the actions that direct the plot like conflict and movement. Then, using that plot outline, fill in the spaces by writing the narration and dialogue for your short story. Note how your outline can constrict, but also how it can direct and guide what your creative side wants to do. Allow the outline to be your friend. Compromise with it, allow it some space and some influence over you, but do not allow it to control you.