I see a couple presents under the tree.
Problem. Grammatically, that sentence is missing a word.
I see a couple of presents under the tree.
There are a couple of hot cookies on the counter.
I have a couple of stops yet to make.
Unless you are talking about two people with a fondness for each other, you need the word "of" with "couple." Maybe it's old fashioned, but for me, leaving off the "of" is incorrect, though I see it done often.
So what are your writing pet peeves? What brings out the rant in you?