The rise of "citizen journalists" is a double-edged sword.
For every video of an innocent person beaten by the police will be the fired federal worker accused of racism.
It is not the act of posting or writing that makes one a journalist, but the act of responsible reporting.
By assuming that mantle with a blog or a camera, you are responsible for the information you post. Don't just claim to want the truth, seek it: ask multiple sources for information and actually report it. Examine the facts and ask the hard questions. Don't just run with a "too good to be true" video — there's no such thing.
Be a skeptic.
Oh, and verify, verify, verify.
Even journalists on reputable media get it wrong. I would like to blame that on the immediacy that technology affords us, but it's always user error. Technology is a tool. It's the people who make it reliable and useful, and in the end it's the reponsibility of the media to get it right before they let it go.