Who are the parties involved in your topic? Are there interest/advocacy groups; what are their positions? Is there an individual that is addressing or instigating the issue? Does it involve a company? What do you know about that company? Are there policy questions that think tanks are writing about? Are there local, state, or federal laws? What led up to the event? Recognize the cultural, organizational, historical, political and other contexts of the information gathered. Fact check by finding the information in multiple credible sources.
To fact check, compare entries on a variety of sources.
Here are some Google Docs from Journalism practitioners