Verify every claim against a primary source wherever possible. For numbers, check the original report rather than a secondary article that repeats it. For quotes, confirm the wording from a recording or transcript, and note the date and context. A quote that is slightly wrong can damage trust far more than a late story.
Images and video need the same care. Reverse-search photos to find their earliest appearance, confirm the location and date, and label any file that is illustrative rather than documentary. Keep a simple log of what was checked, by whom, and when, so corrections can be traced quickly if something later turns out to be wrong.