As writers, we strive for perfection: that pristine copy free of grammatical errors. But it doesn’t always come easy. So, we’ve rounded up the most common pitfalls that cause an editor to take a red pen to your piece — and possibly skip you for assignments.

Mistake No. 4? Overusing em dashes. “Too many in one article (or worse, paragraph) can have the opposite effect and actually cause the reader to disengage. It’s the equivalent of extra exclamation points or writing in all caps,” writes mediabistro.com contributor Kristen Fischer.

Find out six more egregious errors and how to avoid them in 7 Grammar and Copy Mistakes Almost Every Writer Makes. [subscription required]