Suzy Welch: The embarrassing (and common) mistake that can cost you a job offer

You wrote a dazzling cover letter, aced multiple rounds of interviews and sent thank-you notes to everyone you met with. Now all you've got to do is sit back and wait for an offer letter, right? Wrong. The final, deal-sealing step in any interview process is a reference check, and failing to adequately prepare your references is a blunder bestselling management author and CNBC contributor Suzy Welch calls "really embarrassing and totally avoidable."