The most important part of writing is rewriting. I learned early on in college that it's important to just get something down on the paper. Even if the thoughts aren't completely coherent, or that perfect witty introduction, you can, and should, always go back later to revise your initial thoughts into well crafted writing.
There are three things that as a journalist I must focus on to make my writing the best possible: not making errors that can damage my credibility, make the writing clear, and avoid factual errors at all costs.
Credibility
Any errors I make as a TV reporter are broadcasted out to an audience beyond just my peer group. Errors damage credibility because the audience will not trust that the reporter has done the research and really knows the story they are trying to tell.

In my own life, I've seen how errors damage credibility. I was asked to take a survey for a graduate student at an East coast college. It was about being a member of The Church of Jesus Christ of Latter-day Saints. The problem? The graduate student did not write the name of the church
correctly. This is a simple problem with a simple solution, but she neglected to do it, making me question the validity of the survey and possible results.
Clarity
In TV writing, you words are meant to be heard, not read. That means that clarity is especially important because your audience only has one chance to get all the meaning and content out of your writing.
I purposely write in a conversational, but professional tone. This means using simpler words and using visual representations of what I'm writing. I always try to show what I'm talking about on the screen to reinforce what I say.
Errors
Factual errors are journalism-suicide. The job of a journalist is to inform the public of the on-goings in politics so the public can make informed decisions. This is another credibility issue. You can easily lead the public astray by publishing, and not correcting, false information.

This is an issue that
NBC Nightly News host Brian Williams is facing right now. His factual errors has misrepresented him to the public, and now that the truth is coming out, people are calling for his resignation. People trust journalists and will take any reason to lose that trust.