References are an integral part of the hiring process, but many candidates don’t spend the time on them that they should.

According to a survey CareerBuilder conducted a few years ago 80% of employers do contact references when evaluating potential employees, and 16% do so even before contacting the candidate for an interview.

This would indicate that choosing them wisely and preparing them accordingly is imperative to your job search and career success. But it seems that many a job seeker is skipping this crucial step.

The CareerBuilder survey also found that three out of five employers had at some point encountered a reference listed on an application that didn’t have good things to say about the candidate. Sixty-nine percent of employers, meanwhile, said they have changed their minds about a candidate after speaking with a reference, with nearly half – 47% – reporting they had a less favorable opinion. Only 23% percent reported having a more favorable opinion.

That’s bad. You want the potential employer to call a reference already thinking you’re great. But you want them to come away from the conversation thinking you’re even better than they thought. You want the reference to really bring it home. You want them to sell you.

Here are some tips on how to prep your references to make that scenario more likely.

Ask first if they are willing to be a reference. No brainer? Nope. The survey also found that 15% of candidates had listed someone as a reference without giving that person a heads up. Are they crazy? Nobody wants to be blindsided by a stranger calling them up out of the blue to ask them to discuss another person’s potential value as a job candidate. That is really putting someone on the spot and they’re just as likely to resent you for it as to speak highly of you.

Make sure they actually do like you and think highly of your skills and qualifications. Don’t assume someone is going to say glowing things about you. If you ask and they say yes, you can probably assume they’re willing to be positive but if you’re not certain, ask. One possible scenario is that they barely remember anything about you. Their memory might need a jog.

Tell them what you want them to say. Go over the details of the position for which you are applying. Explain what the job entails, what the requirements are, and how you think your core competencies are a good fit for the position. Ask the person whether they agree. Make sure they are comfortable recommending you for these specific competencies. So, if the position requires close attention to minute detail, and the person you’ve asked to refer you says “Actually, you’re more of a broad thinker and your attention to detail is a little lacking,” you might want to reconsider using them.

Ask whether they have any concerns or reservations. Now is the time to ask, in case you haven’t covered any potential negatives. It’s an awkward question and you might not get an honest answer, but you should still ask whether there is anything negative they might say. There’s a good chance that they wouldn’t even if they wanted to. This is because people are concerned about being accused of slander and will often err on the side of caution. There are even companies that refuse to give references for this reason. But you can’t know for sure. And even if the reference doesn’t bring it up themselves, a savvy HR person knows to ask the right questions, like whether you’re punctual or well liked.

Cover these bases and you should be fine.

Even better, be so good at your job and so well liked that you won’t ever have to wonder whether people will say positive things about you because it will be a given. That’s what we all should be aiming for. But you should still ask before using someone as a reference. That’s what well-liked professionals do.