You may have heard before that you should look for a job before you need one. The same can be said for recruiting: look for recruits before you need them, especially for those hard-to-fill positions. LinkedIn Recruiter is a great tool to use, and so is good old-fashioned networking. But recruiting passively is even more effective; that is, getting pre-qualified referrals from people who are sure to call you back. Here are some tips on how to do this.

1. When searching for referrals on LinkedIn, don't just consider peers. Look instead to their best connections and get those names, such as the people they have mentored or who mentored them, and their vendors, customers, and consultants.

2. Monitor your results. Keep track of how many people call you back, who is interested in talking about the position you are offering, how many are qualified, and how many referrals you get per call.

3. Let your referrals know that you're not looking for people who are looking. Instead, ask them for the best person they know who is definitely not looking, but who is open to discussing a possible career move. Try to get three referrals per call.

4. Only call people who will call you back,and who are worthy; that is, they are qualified for the job or know someone else who is.

5.In your email, suggest that you would like to have a discussion around what could potentially be a significant career move for the person, and have proof of that; for example, mention that the copany has just merged with XYZ Inc. and that you are looking for a project manager to lead the first project. Mention the name of the person who gave you the referral.

6. If the person you contact is interested in hearing more about a possible career move, get them to tell you more about themselves before you tell them more about the job. As they give you the information, look out for gaps in their background that your job would fill, then mention these as reasons to go further with the discussion. But if their gaps are too big, then focus on getting three referrals instead.

7. If the person you are talking to says she is happy where she is, then persistence on your part is key. Don’t give up until you have given them the full information they need to make an informed decision. Even if the person is still not interested, you can still get three referrals.

8. Become a person worth knowing. Be a top recruiter who handles top jobs. To do this, you must know your industry well and also your competition. LinkedIn’s Recruiter product gets you in the big leagues.

Convert your list of names into great hires. This is the essence of great recruiting.

Do share your tips with us on how you are able to get top hires.