After practically growing up with the Internet, I think the most important thing I've learned is to not assume something is true unless you've got other sources that back it up. In fact, I've really honed my Googling skills over the year, and I use them. If something feels off or like it needs double checking, I jump on it.
Sure, there are still times where I don't bother to look into something or am falsely convinced by something, but usually, I wind up working out the truth eventually. Overall, I'd say I'm pretty good at knowing when something isn't a good source or someone's saying something that's wrong. And for any big claims I see, I definitely need to go find another source that helps confirm it, just in case.
It blows my mind that there are still people out there who never seem to check things. I don't know how they've never learned that that's a smart idea. But you see fake facts being spread around over and over again, and it really gets on my nerves, especially when I see the same false information for the tenth time. I can't help but ask myself, "Why is this still going around? Haven't enough people looked into it and confirmed that it's false?"
But I can't be the Internet police who jumps in and informs someone every single time they spread false information. Besides being obnoxious, I don't want to put in the time and effort of that. Still, it drives me crazy. It's one of my biggest pet peeves, and the Internet makes sure to provide me with more than enough examples of it.