When you're looking for a job or internship, particularly in a tough market like this one, there's nothing worse than leaving a prospective employer with some sort of bad impression. Unfortunately, though, there are many ways you can do just that, often without even knowing it.

In most job-filling situations, the employer has the luxury of choosing from several well-qualified applicants, all of whom could probably do the job. It is then that the little things,like the common but often unrecognized mistakes described here, almost always come into play. Make sure you avoid them, so they don't cost you a shot at the job.

1. Using a Cutesy Email Address for Correspondence

Example: cutiepie2 @ domain.com  or -- far worse -- sexkitten @ domain.com

You Might Think: It's a clever, memorable email address everyone will get a kick out of.

The Employer Will Probably Think: I can't believe someone would actually list this email address on her resume, let alone use it to correspond with me. Will she do the same thing on the job if I hire her? Yikes!

2. Putting a Silly Message on Your Answering Machine

Example: "A is for academics, B is for beer -- and one of those reasons is why we're not here. You know what to do, OK?"

You Might Think: Mine is the funniest answering machine message this side of the Mississippi. My friends will love it.

The Employer Will Probably Think: Good lord, this person probably lives in Animal House. And I just can't risk interviewing, let alone hiring, someone like Bluto or Flounder. Sorry, Charlie. Click.

3. Sending Your Resume and Cover Letter Without Proofreading

You Might Think: Everybody makes mistakes, even employers. So if there's a mistake or two on my resume, no big deal. The employer probably won't even notice, much less care.

The Employer Will Probably Think: Everybody makes mistakes, even employers. But making more than one minor mistake on a resume or in a cover letter is unacceptable, and often, even one is too many. How do I know this person will proofread the letters he writes to shareholders? What if he someday leaves a zero or two off one of our financial statements? I better put this resume aside and look for someone who's more accurate and thorough.

4. Winging Your Interviews Instead of Preparing Thoroughly

You Might Think: I'm good at thinking on my feet, and if I get stuck, I'll just BS my way through, like I've done on many an essay exam. Besides, they can't expect me to know everything about the company.

The Employer Will Probably Think: This person clearly knows nothing about the company, nor has she made any effort to learn more about us and what we do. She must not really care whether or not she gets the job. I want someone who cares. Oh well, maybe the next person will be better.

5. Failing to Send Thank-You Notes After Interviews

You Might Think: A thank-you note? You're kidding, right? Do people even do that sort of thing anymore?