Think about your audience --- the kind of publication you are writing for, who is reading it and what issues are important to them. This will help you choose a subject. Once you've decided on a newsworthy topic, you need to gather all the facts you can get your hands on.
Search for every piece of information that pertains to your subject. Review articles that have already been written about your topic for background information. Conduct interviews with anyone directly related to the subject, preparing a list of questions in advance. Make sure you collect all the information you can on both sides of the story.
The five W's help reporters remember all the important facts to include in a news report: who, what, why, when and where. Generally, you should include all W's in the first paragraph --- the lead --- of your news report. Although certain news stories may not require every "W" be covered, it's still a helpful device to use to ensure that you've included all necessary information at the beginning of your report.
News reports often follow a certain structure. The lead paragraph is meant to pull the reader in and spark interest in the topic. And don't forget those 5 W's. The next four or five paragraphs --- the body of the piece --- are used to elaborate on what you discussed in the lead paragraph. Include facts and relevant quotes you obtained during your research. Quotes add color to a news report, as long as they don't simply reiterate what's already been said. The last paragraph should contain a thoughtful ending that might also be somewhat provocative and that leaves the reader thinking. News reports are usually written with the most important information up top, so that the last paragraph or two could be chopped off without major consequence if space were short.