Perspective is more than just a question of writing style. It is a question of power. Should you be the omniscient god, knowing every thought that runs through your characters' heads? Or should you confine the narrator's knowledge to what only she knows, thus focusing on a more intimate subset of the story? The answer may vary by writer, or it may vary by story. Either way, it is a decision that must be made even before you can begin to plot your story.
For the sake of thorough analysis, let's take a cursory look at the three different types of perspective.
First-person perspective is the way that we normally talk, the way that we tell a story in which we are closely involved. It uses the first-person pronouns "Me," "Myself," and "I" extensively.
Processing the events playing out before me, I raised my pistol to eye level and threatened the intruder.
This is a dominant form of writing, giving authority to every event since the speaker is an eye-witness to what happens. There are drawbacks, however, as the author must establish a level of integrity for the narrator or risk the reader not believing the characters.
Second-person perspective is normally reserved for a list of instructions, though it can have its place in other forms of writing. Most of the time, a sentence written in second-person perspective has no subject, leaving it to be understood as "You."
Embrace your love with both hands and your tentative kiss will become a passionate moment.
In this form of writing, the reader is more directly involved, as the sentence reaches out and draws you in to what's going on. If you're writing a technical manual or a guide to rebuilding a Volkswagen engine, you'll want to adhere closely to this style. However, if you're writing a formal essay or a work of fiction, you might want to use this perspective sparingly.
Christine gripped the reins, gritted her teeth, and closed her eyes, hoping that her thoroughbred would make the jump over the gate.
The main advantage to this perspective is that no action is questioned. It is as if God Himself were telling the story, and the decisions made by each character are without reproach. However, this lacks the intimacy held by first-person perspective, and the story quickly becomes bigger than the plot itself.
When you sit down to write a story, you have to ask yourself a few questions in order to determine the best perspective from which to work. Is your story focused on a single person, detailing her growth as she overcomes adversity? If so, then first-person perspective is probably the best choice. Does your story chronicle the events of a killer epidemic that sweeps the entire planet? In that case, third-person perspective would be the obvious position to take.
That's not to say that you couldn't experiment with a different perspective. If you were trying to tell the first story from the third-person, it would be a challenge to properly relate your reader to the lead character. Likewise, in the case of the epidemic, if you followed only one character, you would have trouble convincing the casual reader of the global impact of the virus.
One of the best examples of an interesting take on perspective is Bram Stoker's Dracula. In that novel, Stoker uses first-person perspective from a variety of different sources through their journal entries. We are connected to each individual, but at the same time are given many different portals into the story.
Why is it important to determine the perspective before writing the plot outline? It's simply because you need to know from the beginning how your story will progress. Depending on your choice, you will be faced with interesting possibilities of working through certain situations and other possibilities will be eliminated.
For example, if we are writing from first-person perspective, then we don't automatically know the motives driving the stranger that comes to our protagonist's aid. Instead, we have to plot around that, either by simply having the stranger state his motives, which is not very interesting, or having our narrator catch glimpses of the stranger's actions that reveal his characteristics. Knowing in advance that this stranger does not have a voice exposes the need for justification through his actions.
There is no rule that says a story may only be written in a single form of perspective. In fact, it would be a very boring world if this were so. Dialogue, of course, takes place in first-person, even if the rest of the story were in third-person. Interjections of second-person perspective can be used as a device to make the reader a part of the story. Take a look at the following paragraph and notice its use of perspective.
You can never tell how your day will go from the way that you wake up. Your back might creak when you rise, or you may feel clear and refreshed; still, you have no idea of inevitable events. When Dirk aimed his harpoon gun, the tenor of the day changed. It was neither a shark nor a whale that was in his sights, but the target was in no less danger. I had no idea what impalement would feel like, and I wasn't ready to find out. All that I could think of was how I wanted to crawl under the covers again and sleep the day away.
Here we see three different uses of perspective. The first two sentences are written in standard second-person. They are rhetorical in nature, but serve to captivate the reader. The second two sentences are standard third-person perspective, detailing and describing the actions of a troubling antagonist. However, we aren't given a clue as to Dirk's motive; that remains a mystery. The final two sentences, in first-person perspective, reveal the real threat to our protagonist and give us a vision into her mind. Though faced with impending danger, she does not fret but casually wonders how her earlier decision (to get out of bed) could have changed the course of her day. What kind of person could be so calm in a perilous situation?
We have learned that there are significant advantages and disadvantages to each style of perspective. Any budding writer (and even those who are well-experienced) should look through some of their past work and see if they used the best-suited style. Would your story have been better told from merely the narrator's point of view? Could you have given us better insight into the plot from the view of an outsider? Might the story have been more enticing if you had spoken directly to the reader on occasion?
It is important to remember that a picture of a diamond from a single angle shows only a few facets; in order to fully appreciate its beauty you must hold it in your hand. Second to that option, a picture from every angle will reveal the diamond's intracacies. Nothing, however, can outshine that breathtaking shot from the proper angle with the perfect backlighting.