Finding references seems simple enough: approach professors, previous bosses and supervisors from your internships, and you should be all set. Well, not necessarily. For one thing, companies want to know about more than your academic and technical skills before they hire you. For another, that professor who gave you high marks may not really like you all that much. Taken together, your references should give potential employers a view of everything from your technology prowess to your work ethic and ability to learn. Those references should also consist of people you trust to say the right thing, and parry any sensitive questions in a way that makes you look good. So how do you identify the right people? Try following this process:

Make a List

Tom Henricksen, an IT career coach in West Des Moines, Iowa, suggests listing all of your possible references. Consider how well each one matches your needs, then cross off those who don’t fit. Typically, employers ask for three references, but don’t cut down your list that far. “You want to have a bullpen so you can change things up if you have to,” he said.

Pick People Who Know You Well

As you evaluate potential references, think about how people have interacted with you. For example, Henricksen said, your engineering professor may be well-known in a particular industry, but if you’ve only met with her face-to-face a handful of times, she’s probably not going to fit as a reference. “Think about your experiences with the person,” he explained. “You may have worked with someone who’s impressive, but they can’t speak to your work habits, things like showing up on time.” In other words, your references should be able to give employers an idea of the type of worker you’ll be.

Mix It Up

Since you’re just graduating, employers expect to see a professor (or even two) among your references. But don’t limit yourself to campus contacts. Companies want to hear about your performance in a business environment, so include managers or professionals you worked with during internships or technically-oriented volunteer projects. You can include supervisors from other jobs, too—like the director of the summer camp you worked at—but they won’t pull as much weight as someone who’s worked with you in a tech-related capacity.

Mix It Up II

Match your references to each employer and role. Some companies may be more interested in hearing from contacts with a background in software development, while others will want to know about your math skills. As you research each company, think about who on your list aligns best with its business and the job you’ll be taking on.

Ask

Always—always—ask someone to be a reference before you give out their name. For one thing, it’s a basic courtesy. For another, the employer won’t get a great impression if your references sound surprised when they get the call from HR. Finally, the references themselves may be peeved by the fact that you didn’t check in with them, and that can complicate a valuable relationship.

Don’t Assume People Will Say Nice Things

It’s natural to think that anyone who agrees to speak for you will say nice things. But don’t leave that to chance. A number of tech professionals have stories of references who have bad-mouthed them despite being cordial on the surface. Henricksen thinks there are a few things you can do to winnow out those who might be toxic to your job search. For one, pay attention to their reaction when you ask them. “If someone seems put off or hesitant, cross them off your list,” Henricksen advised. Also, follow up with them to see if the employer actually reached out; if they did, ask about what they said. If the reference seems defensive, “that’s a clue.” Henricksen also suggests having coffee with references to make sure your relationship is where you think it is, and that they can speak to an employer's interests. Henricksen also stresses the importance of networking, which is “often overlooked in IT.” Developing your network provides you with a growing pool you can call on whenever the need arises for references over the course of your career. The bottom line: Tapping references isn’t something you do on the fly. Take the time to put together a list of people who know you well and will be your advocates.