When you write a pitch, report, blog post, or company statement, how certain are you that you're using words correctly? Sure, you use a spell-checker, but that catches only spelling mistakes and the simplest of grammar goofs.

You need to do better because misusing any of these common phrases will affect some readers the same way an instrument played off-key affects a professional musician. Your writing-and you-will lose credibility in their minds, even if they're not aware of it. I know because I sometimes am one of them. I picked up a book by an acquaintance this morning figuring I'd give it a try, but when I came to the word "eke" used incorrectly on the second page, I put it back on the shelf.

Every one of these errors is a pet peeve to some people, including some of the people you're trying to impress. So even though some of these may be arguable, and all of them are inarguably nitpicks, it makes sense to get them right. There's no sense in having someone ignore your ideas just because they're distracted by your grammar.

1. It's instead of its.

It's = "it is." Its = "belonging to it." I've written these two sentences in the margins of other people's writing hundreds of times. Almost every article about grammar seeks to correct this error, yet it remains an incredibly common error, easily found in billboards and advertisements, never mind websites.

To those of us who know better, it's like fingernails on a chalk board so please don't do it. Every time you write "it's" stop for a moment and ask yourself if the sentence would make sense if you replaced it with "it is." If the answer is no, use "its" instead.

2. Apostrophes in plural words.

An apostrophe serves one of two specific purposes. Either it's standing in for a missing letter (don't instead of do not) or it indicates possession, as in Joe's car. If neither of those applies, then don't use an apostrophe no matter how much you want to. The disco era was the late 1970s, not 1970′s. And that couple you met last night were the Smiths, not the Smith's.

3. For you and I.

I is the subject of a sentence, whereas me is the object. But people who've heard too many children get scolded for saying things like "Me and Jim went to the store," tend to overcompensate and use I whenever in doubt, as in "Sandra brought a present for Jim and I."

There's no need for a confusion. Just use a very simple test that will never steer you wrong-remove the other person from the sentence. Do that, and "Sandra brought a present for I," will sound just as wrong as "Me went to the store."

4. Lay down.

"Go lay down," is so commonly used it may sound right but it's dead wrong. To lay is a transitive verb which means that you can't just "lay there," you have to lay something. An egg for example. To lie is probably what you mean, as in "lie in bed" or "just lie still."

The source of the confusion is that the past tense of lie is lay, as in "yesterday I lay in bed all day." Don't let it throw you.

5. Hopefully it won't rain.

Nope, you mean I'm hoping it won't rain. Hopefully is an adverb which means it can only be applied to a verb as in, "He looked hopefully up at the sky, wishing for the clouds to go away." Don't use hopefully when you mean "I hope."

6. Alright.

Is it a word? Is it not a word? There's a lot of controversy out there. Here's what Merriam-Webster has to say: "Although the spelling alright is nearly as old as all right, some critics have insisted alright is all wrong."

To my mind the point of good writing is to get your message across which you may fail to do if some readers are annoyed at you for using alright when they don't believe it's a real word. So why do it? In every situation, all right works just as well.

7. Different than.

This is something I used to get wrong until I took a job at a company where this was one of the editorial director's pet peeves. It's a similar case to alright. "Different than" has its defenders who point out the phrase has been in common use for many years. But strict grammar sticklers prefer "different from." Again, why annoy people for no reason? Use different from.

8. Using that and which interchangeably.

When to use that, and when to use which, is a source of ongoing confusion. That precedes a defining characteristic, necessary to the meaning you want to convey. Which precedes something that's not needed for the point you're trying to convey. Thus, if your friend wants to do the laundry and asks where the dirty clothes are, you might answer "The clothes that are dirty are in the hamper." As opposed to the other clothes that don't need washing.

On the other hand, if your friend is trying to remember where he left his clothes, you might answer, "Your clothes, which are dirty, are all over the floor." Non-necessary clauses using which should be separated from the rest of the sentence by commas.

When in doubt, use this test: Take the clause out of the sentence and see if it still conveys the needed information. "The clothes are in the hamper," doesn't really answer the question you were asked. "Your clothes are all over the floor," does.

9. Using between when you mean among.

Between refers to two distinctly delineated people, objects, or groups. "Between you and me," is correct. So is "The War Between the States," because even though more than 30 states and a bunch of territories were involved in what most of us call The Civil War, They were divided into two distinct sides. "He was hiding between the trees," is only correct if the person hiding has one tree on either side of him, and there are no others. If you're talking about more than two of something, use among.

11. I feel badly.

Badly is an adverb, which means it applies to the manner in which you feel, not what you feel. If you have nerve damage to your hands such that you can't really tell what you're touching, then you do indeed feel badly. But if you're sad or upset about something, you feel bad.

12. I feel we don't have enough money in the budget for this project.

While we're on feelings, let's be clear about what a feeling is. It's an emotion or sensation-you feel insulted, afraid, angry, hopeful, tired, hungry, or cold. It's not an opinion or a matter of judgment. So if you're stating something that you think or believe, use one of those words or something similar, rather than "feel." This is one I get wrong myself, often in speech and sometimes in writing but it's better to get in the habit of only using the word feel when you really mean feel.

13. There were less participants than last time we ran this program.

No, there were fewer participants. Individual items that can be counted take "fewer." A unit that's smaller than one, or something more amorphous or intangible such as time or takes "less." "There was less interest in our program than last time," or "There was less of a crowd than last time." Or, if things were really bad, "It took less than five minutes for the audience to leave after we began our program."

Those are my top grammar pet peeves. What are yours? Please feel free (a sentiment!) to share them in the comments.