Using "try and" instead of "try to".
For example, "I am going to try and use this expired coupon".
No, no you're not.
For one, that's just plain wrong. That is, trying TO use an expired coupon. Pay attention to the date, for God's sake!
Two, you don't "try and" do anything. You try TO do something.
I can't believe how often I come across this grammar mistake. Sure, one can expect it on the web and on blogs. But Writer's Digest books? And writing magazines? Gah! Where the hell is the editor?!
So, please, do me a favor lest you make my blood pressure knock out the ceiling: use "try to", not "try and"!