|A pair of pears|
Until I run across something new, this is all I have in the queue for grammar peeves. If there's a grammar issue you struggle with, feel free to post about it in the comments, and I'll post about it at some future date.
Homonyms are more of a spelling issue than grammar, but they're just as distracting as poorly constructed sentences, and they do contribute to writing mechanics issues. Homonyms may also be called homophones. They're when words that sound the same are spelled differently, depending on meaning.
Here are a few commonly confused homonyms:
Affect = Verb, as in to affect the outcome
Effect = Noun, as in to have an effect
Buy = To purchase
By = A preposition, meaning "near"
Bye = Short for "goodbye"
Cite = To quote
Sight = Vision
Site = A location
Hear = To perceive with the ear
Here = In this location
Lose = Opposite of win
Loose = Opposite of tight
Than = Used when comparing two things
Then = Used to indicate a point in time
They're = They are
Their = Belonging to them
There = At a point in space
To = Preposition, meaning "toward"
Too = Additionally
Two = The number 2
Whose = Belonging to who
Who's = Who is
Your = Belonging to youI've already written about when to use an apostrophe, so, if that's all you need to stop using the wrong word, that post is there for your use. If you'd like a more comprehensive list, this is the longest list of homonyms I've ever seen.
You're = You are
I can't say I've never written the wrong word. Sometimes, I didn't even pick one that sounds similar, leaving me to puzzle over what I possibly might have been aiming for when I go back to edit. So I do know how this happens. You get caught up in how the words sound in your head, and, because your inner editor is off, you're not paying attention to whether they're correct.
In the first draft, that's perfectly normal, and to be expected. But if, in later drafts, you don't catch it, and your editor doesn't, either, you're going to look mighty foolish when the reviews come out.
And, if you don't know to look for these in the first place, you're going to have some difficulty ever leaving the slush pile. If you don't know if you're confusing any homonyms, let a picky friend read a few chapters of your manuscript, and he or she should give you a good idea.
Once you know which homophones to look out for, you can do a Ctrl+F (if you're using Windows—Mac is Cmd F), and check each usage to determine if you wrote the correct one. Taking homonyms out of context, or even reading your manuscript backwards will illuminate a lot of this problem, but only once you're aware of it.