are you making these job reference mistakes?

It turns out that it’s possible for your references to diminish your chance of getting the job without even saying a word. Here’s a recent experience I had when checking the references of two candidates I had been torn between.

Candidate #1 gave me the phone numbers of three former managers. I reached each of them easily and the references were strong.

Candidate #2 also gave me a list of references. One of them had a phone number which, when I called it, turned out to be disconnected. Another had a number that was answered by someone else, not even at the same company. I had to contact the candidate several times to get correct numbers. This raised red flags about the candidate’s attention to detail and whether she doesn’t tend to check things out before handing over potentially wrong information. In the position she was applying for, that could be disastrous.

The lesson? Call your references yourself ahead of time. Not only is it smart to give your references a heads-up that they may be called by a prospective employer, but if you haven’t talked with them in so long that their contact info may have changed, you want to find that out and track down the new info — not give the reference-checker bad or outdated info.

Other ways candidates sometimes mess up with their references:

* Not staying in touch. If your old boss who will give you a glowing reference leaves her company, you need to be sure you’ll have her new contact info. I’m always surprised by how many people who need to scramble to figure out how to get in touch with the former managers I want to talk to.

* Not offering up managers as references. If all your references turn out to be peers or people who didn’t directly manage you, I’m going to wonder what you’re worried your managers will say. (And I’ll ask to talk to them anyway.)

* Using friends as references. If the reference-checker discovers that the reference is a personal friend, it undermines that person’s credibility. I was once talking to a reference who mentioned that he used to date the candidate — this is not a good idea.

I originally published this at U.S. News & World Report.