While most career advice focuses on how to succeed, we can all learn valuable lessons by dissecting career failure as well. Workplace experts offer insights into some of the top ways workers undermine their own careers and jeopardize their career development.

1. Not Taking Your Education Seriously
If you party too much in college and end up with a run-of-the-mill 2.5 GPA, you’ll be passed over for the best entry-level jobs, says New York City-based executive recruiter and coach Brian Drum of Drum Associates. Not finishing your master’s degree is another way to hurt your career development goals, adds Anne Angerman, a career coach with Denver-based Career Matters.

2. Not Having a Plan
In the current poor job market, you may have defaulted into a career you aren’t crazy about. That’s OK, as long as you develop career plans to get where you want to be. “Think of every job you take as a stepping-stone to your next job,” Drum advises.

3. Lying
You’ll lose professional credibility in a hurry if you lie, from exaggerating on your resume to getting caught fibbing on Facebook. “If someone calls in sick to work and then that evening posts a photo on Facebook of their extra day vacationing in Cabo San Lucas, that’s a big problem,” says corporate etiquette specialist Diane Gottsman of the Protocol School of Texas in San Antonio.

4. Sullying Your Reputation on Facebook or Twitter
Social media can harm your reputation in other ways, too. Personal posts and tweets from work -- when you’re supposed to be doing your job -- can tag you as a slacker. And the content of your posts or tweets can come back to haunt you as well -- you never know who might stumble upon those bachelor-party photos. “You need to assume that every boss and potential employer knows how to use Facebook, Twitter and MySpace, and post from the standpoint that everyone is watching even if in reality they’re not,” Gottsman says.

5. Not Respecting Professional Boundaries
Sharing TMI about your personal life with colleagues is unprofessional. “Your coworkers don’t want to hear about your fights with your husband,” Angerman says. On the other hand, if you’re ultraprivate and work with a chatty group, join the conversations occasionally so coworkers don’t resent you.

6. Gossiping, Slandering, Excessively Criticizing
If you publicly bash fellow employees, the boss, the board of directors or even your competitors, you’ll be perceived as negative at best and a troublemaker at worst. The ramifications can be broad and long term, Gottsman says. “Industries are tight,” she says. “You don’t want to be the one who started that rumor about the head of your industry.” As far as bad-mouthing competitors -- what if your company merges with a competitor, or you want to work for one someday?

7. Carrying on an Inappropriate Relationship with Your Boss
A romantic entanglement with a boss can do real damage to your ability to collaborate with peers. "When you get involved in a drama or in something unethical that can be brought out in the open, you're asking for trouble," Gottsman says. Even getting too chummy with a boss can cause jealousy (as well as other potential problems). When it comes to your boss, keeping things professional is always the wiser choice.

8. Not Controlling Your Alcohol Intake or Libido
Getting drunk at the office party or on a business trip damages your credibility. Ditto a romantic, ahem, “indiscretion” that your colleagues know about.

9. Job-Hopping Just for the Money
Job-hopping -- in moderation -- may not automatically disqualify you from a position. “But it gets to the point -- like if you have seven or eight jobs by the time you’re 35 -- that employers are not going to want to invest in you,” Drum says. Also, if you have leadership aspirations, keep in mind that the top dogs of many large corporations have been with those organizations for long periods, he says. Additionally, many companies have “last in, first out” layoff policies, which could leave you out of a job if you never stick around long enough to build tenure anywhere.

10. Losing Touch with References
You’ll kick yourself later if you leave a job without collecting personal contact information from colleagues who can serve as professional references for you in the future. “If you were forced to leave a job and you can’t ask your boss for a reference, hopefully you’ve built up some rapport with a colleague and can ask them,” Angerman says.

11. Leaving a Job on Bad Terms
Don’t become a lame duck when you’ve got one foot out the door, Drum says. “The employer only remembers about the last five minutes you were there,” he says. Give proper notice and don’t leave a mess behind. And by all means, do not make a huge dramatic production of it when you quit, complete with cursing, slandering and throwing things, Gottsman advises. “It’s very difficult to get another job when you’ve left destruction in your wake,” she says.