Want to refer a friend? Even though it can seem like just a small favor in a tough job market, it's important to think carefully before recommending a friend to someone in your professional network.

Referring a friend to a former colleague or someone in your network is fairly simple for most people, but if your friend is less than stellar at the job, it can backfire and reflect poorly on your own career, experts say.

Because you know your friends from a mostly social perspective, vouching for them on the job may affect your credibility with someone in your network.

Here's what to consider before recommending a friend:

How well you know your friend

Referring someone whom you've met just a few times or haven't been in contact with in years could be risky.

Before you press "send" and pass on his résumé, it's important for you to evaluate what you know about the person and how he acts in the workplace.

"Consider first if you know the person well enough to recommend them," says Chris Posti, president of outplacement firm Posti & Associates.

His employment history

Even if you've never worked with your friend, finding out his employment history before sending out a recommendation is a good move. Think about it objectively before making a decision.

Don't refer the friend if "your friend's general employment history is spotty for reasons you know to be negative," says Ann Dunkin, the operations manager at Attorney Resource Inc. who handles human  resources issues.

Should your friend get a negative reputation on the job, it could put you in an uncomfortable position.

Would you vouch for him to human resources?

Even if you just casually want to put your friend in touch with a current or former boss, this could result in the company asking for a formal referral. Consider whether you would "be willing for that employer to contact you concerning your friend," Dunkin says.

It's easy to empathize with a job seeker, but formally vouching for his skills on the job is a more serious decision.

If you're not up for it, consider just providing a contact's email or phone number but asking your friend to not mention your name.

Examine your own reputation

Sometimes there are other more personal reasons for asking that your name not be mentioned. Your own reputation at the company or with a former boss can influence how your recommendation is perceived, Posti says.

"Maybe your friend doesn't know that you are not on good terms with your boss or that your work is just average," he says. "Your friend may be better off pursuing the job on his or her own." So even if you're totally positive about your friend's candidacy, recommending him may still not be your best bet.

Predict your own working relationship

Before making a recommendation, think ahead to what your working relationship would be like down the road.

For example, if your friend works for your current company and is now reporting to you, it's important to feel comfortable with the new dynamic. Or if the friend is a gossip, it can be valuable to keep him or her away from your current boss.

Ask yourself, "Does the person know any skeletons in your closet that might be spilled out over drinks at the company's Christmas party?" Posti says. Before passing on his résumé, think carefully about how it could affect your career.