The most common error I see is the improper use of commas. Here's the deal. When joining two independent clauses with a conjunction, you use a comma. "I went to the store, and then I took a nap."

When one of the clauses is a dependent clause, you don't put in the comma. "I went to the store and then took a nap." Because we are so used to seeing "and" and "but" preceded by a comma, people tend to always put them in, but that's incorrect.

Of course, commas are also correctly used in series (I bought bread, milk, and eggs) and to set off parenthetical phrases (The best way to see a country, unless you are pressed for time, is to travel on foot.)

When using commas in a series, it has become common to leave off the last comma. This is fine for simple series like the one above, but be sure to include it in a more complicated series to make things easier for your reader.

Hyphens can be extremely confusing, and many people use them incorrectly. Here's the scoop.

Compound modifiers should be hyphenated. For example, a pie-eating contest. Pie eating describes the type of contest.

Where people go wrong with hyphens most often is hypenating words that are often used as modifiers even when they are not modifying anything. For example, we often see state-of-the-art hyphenated, as in: "She had a state-of-the-art stereo system." But if you were to say: "Her stereo system was state of the art," hyphens are unnecessary (and incorrect).

Don't be afraid to use more than one hyphen if it's called for. We don't write "a hot dog-eating contest." We write "a hot-dog-eating contest." Similarly, it's "The 20-year-old man was too young to buy alcohol."

The exception to the rule is when the modifier includes an adverb. As in, "Steve has a highly developed sense of of style." No hyphen needed.

Remember back in grade school when you were told to only capitalize proper nouns? It was good advice.

Many companies today are in the habit of capitalizing words that are important to them. This is acceptable, to a certain degree, in marketing materials. But if you want to look intelligent to your prospects, keep it to a minimum. No need to say, "The XB2000 is the best Widget of any Widget in the Widget marketplace."

It's also important to remember that just because you capitalize something internally does not mean it's a proper noun in the "real" world. Magazines and newspapers are not going to capitalize it, nor are they going to uppercase your company name just because you always do (that's your LOGO, not your company name).

Here's a good habit to get into. Items in a series should have the same grammatical form.

Incorrect: Three requirements for good health are good nutrition, getting enough sleep, and to exercise regularly.

Correct: Three requirements for good health are good nutrition, adequate sleep, and regular exercise.

If you're responsible for writing or editing company materials such as a newsletter or Web pages, do yourself a favor and develp a style book. This is a "bible" of how your company handles tricky words and situations (decisionmaking: one word or two?).

A good place to start is with the AP Stylebook Take a look through it, see what makes sense and where you want to deviate from it. As you come across words that are in that gray area, make a decision and record it the style book. You can refer to it the next time you come across the word, and you can give a copy of the book to anyone who's going to copy proof your work or others.

When someone inevitably comes into your office steaming mad that you changed his/her copy, calmly either say, "We follow AP style on that," or "That's our company style" (with a nod toward your very-official-looking binder).