Career planning is hot. Career mistakes are cold. But almost everybody does something really, really dumb at least once in a working lifetime.

If you're unlucky, your mistake gets into the news. Recently I read a story about a flight attendant who was fired for posting photos of her uniformed self, striking candid poses on an empty airliner, in her blog. And maybe you remember the rising star consultant who sent out a message describing his last date in graphic detail.

If you're really unlucky, your first guest appearance on a major talk show comes after a mistake, not an achievement.

Most of us manage to hide the live editions our worst case scenarios. But as a disaster planning exercise, here are my candidates for the Top 10 Dumbest Mistakes Made by the Smartest People.

1. Posting a photo of yourself on the Internet in a pose or costume that might raise eyebrows (not to mention red flags) at the office.

Would you post this photo on your desk? Add a framed version to your office wall? Once you've posted to the Internet, you might as well.

2. Wearing a company uniform (or carrying an emblem of the company or standing outside company HQ) while performing Dumb Mistake #1.

It's like having your black sheep brother bring dishonor on the family name. Try not to think about what happens if it's the Family, as in Soprano.

3. Writing a blog about your company "for therapy" and insisting it's for you and your friends.

Therapy should be private. Blogs are written to be shared with the world.

4. Using the company email to send a personal message.

I get dozens of queries every year: "Hi Cathy. I hate my job. Can you help?" All written on their employer's message system, legally available to their bosses and colleagues.

5. Thinking your boss, the HR department or the recruiter is your friend.

Whoever pays their salary is their new best friend. I encourage my clients, "Talk to your recruiter as you would talk to an employer or client."

6. Expecting free career support.

Surprisingly often, I get calls from experienced professionals who ask if we can "just talk" for an hour or so. These days, the only free help comes from your mother.

7. Working extra hard just before your layoff comes.

You've got six months left on the payroll. No matter how conscienetious you are, it's time to do just enough to keep from being fired. Chances are your company expects you to disappear from time to time. Depending on your ethics and your company's policies, they probably expect a flurry of "dentist appointments" and other excuses.

8. Sharing too much personal information.

It rarely helps and often does harm. You tell your boss, "I need to live here because of my family." Your company is the only game in town so everybody knows you're not going anywhere. And you wonder why you're taken for granted?

9. Hanging on too long.

When people really hate their jobs, often they do something to sabotage themselves. They secretly hope they'll get fired. It's scary to admit, "I made a bad decision and I have to walk away." But usually it's better to be a driver than a passenger on your career journey.

10. Worrying too much about mistakes

Sometimes a major mistake turns out to be the best thing you could do. I've met people who asked for all sorts of things because they didn't know any better. They got everything they wanted and more.

And if you've just made a colossal blunder, take heart. Many years ago, a young television journalist sent out a rant against her employer, intended for a few close friends. She accidentally hit the wrong button and her message went out to everyone in her company.

End of job. But her career flourished. And the story became a great beginning to her best-selling memoir.