Ok, this seems obvious. Journalists are inherently bad at math, but we all should be able to calculate a person's age. And to be clear, I am capable of doing that math. But let's say you're looking at court or police documents and it only lists a person's date of birth. Did this person just have a birthday? Or is it still months away? I like to use this age calculator to double check that I have the age right. This is something that's incredibly easy to get wrong. It's also an incredibly stupid mistake. You're probably the only one that is going to double check this person's age. Get it right.
Some of these articles apply more to the UK since that's where this site is based, but they actually have a lot of good tips for how to break into the profession.