According to Welch, acting too casual or relaxed during a job interview is one of the biggest blunders you can make.
She recalls the time when she made this error as a recent Harvard University graduate who was interviewing for a reporting job with the Kansas City Times.
While riding to lunch with a group of editors from the paper she says she remembers asking, "So, what kinda food we getting?" as if they were old friends. She recalls meeting with the editor-in-chief later that day and asking him where he lived, as if she was scouting local real estate.
The next morning, she says, she got a call letting her know that she didn't get the job because she didn't "fit in." "The editor didn't have to explain himself," she says. "I was dumb, but not so dumb that I didn't know I had overstepped."
"Even if you think you're perfect for the job," she warns, you need to always remember, "they are the buyer, you are the seller."
"Do not," Welch says, "let down your guard."
Click here to learn more about how to avoid seeming too relaxed during in an interview
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