It even matters in blogging, I’d argue. Sure, blogging is less formal, and it’s OK to bend some grammar rules here and there if it helps you communicate more effectively. Heck, I’ve certainly bent and even broken my fair share of rules in my blog—intentionally and unintentionally.
However, there are certain grammatical mistakes that you simply shouldn’t break. When you do, it makes you look just plain stupid, to be quite honest. It causes you to lose credibility with your readers—whether that reader is a guest on your blog or a reporter to whom you’ve just sent a press release.
So, which grammatical mistakes should you avoid at all costs?
1. Using of instead of have
This one drives me a bit insane. The phrase is could have, not could of. It’s should have, not should of. And it’s would have, not would of. I understand that when you hear it said aloud—especially in contractions such as would’ve—it sounds like the person is saying of, but they are (one hopes) saying have.
2. Mixing up your, their, and its with their homonyms