A writer can use any writing style depending upon they selection. Writing is a way to communicate with your audience and to convey a message between a writer and his readers.
Ever notice how each writings are being discussed? What kind of techniques does the writer use? Ever wonder how a certain writer communicates with his readers? Like how he states it clearly just to influence his audience? It's like how the writer talks in his writing.
A writer has a voice in his content. Writers talk to their audience just like facing them personally. When a writer uses a third person in writing, it usually uses another character or person which is created inside his content and will be the one who carries the message that the writer is trying to express.
Writing in a third person is more preferable than writing in the first and second person. It always shows formality and it presents arguments fairly.
Many writers find it most natural to write in the first person. In fact, it's relatively easy to fall into the habit. However, writing in the third person is an equally important skill to develop, as you will find that it lends itself well to certain types of work.
If you regularly catch yourself starting a piece in the third person, then unconsciously shifting to a first person POV at some point, you may need a little help. I suggest keeping a visible reminder (such as a Post-It pad on your monitor) that you're supposed to write in the third person voice.
You should also customize your grammar checking software to help you on this end. Whenever you're going to have it pass through a document written in third person, include the self-referencing pronoun "I" among the words it's supposed to flag. That way, you'll catch every instance and have a chance to correct it.
Here's one exercise you can do to train you in writing using the third-person voice:
1. Grab your current favorite novel (or article or story) that's written in the first person.
2. Rewrite a few pages of it (if it's a book) or the whole thing (if it's a shorter piece) in the third person point of view.
3. Don't rush it, take your time. If you're not used to writing this way, the words may not come as naturally.
After writing, compare the two versions:
1. Notice how the change modified the overall mood of the story. What kind of improvements do you notice? What about the newer piece seem inferior compared to the original?
2. List down the advantages of using the third person in this particular case.
3. List down the disadvantages of using the third person in this particular case.
That's it. It's no magic exercise that will suddenly endow you with the ability. However, if you keep doing it several times, you will learn to familiarize yourself with the nuances of third person writing, especially when compared to a first person point of view.