While job boards and your website make it quick and easy for the employer and the applicant alike, they are far less effective than the top three, proven sources of great employees.

1. Former employees

The best source of proven talent is all the great people who used to work for you. When employees leave you to work elsewhere, they often discover the grass isn't greener after all.

In fact, research shows that 20 to 25 percent of employees have gone back to work for a company they once left. Imagine if 20 percent of all the good people who ever left came back to work for you. You'd have instantaneously productive people who require little or no training. All you have to do is ask.

About a month after someone good leaves, call and ask if he or she would consider coming back. And call the great people who left years ago, too. Even if they say "no," you can then ask if they know of anyone else who might be interested.

And don't give your best ex-employees away to your competition without a fight. Anytime someone calls you for a reference on a good or great former employee, you've just been put on notice that your former employee is looking to change jobs. It's the perfect time to call that person to see if you can get him or her to come back to work for you instead.

2. New employees

The second-best source of new talent is every new person you hire. All you have to do is ask them if they've worked or trained with anyone who might be interested in working on your team.

Do this even if you're not looking to hire anyone at the moment. Build your recruiting database now for the inevitable time you do have a need. (It's the only way to avoid desperation hiring.)

3. Current employees

The third best source is all your present employees. Research shows that employee-referred candidates are three times more likely to be a good match for the job. This is because your employees give these candidates much more detailed information about the job requirements and working conditions than you would.

As a result, candidates are only likely to proceed with the selection process if they feel it's a good match. And, because they're such a good fit, referral candidates who are hired are also much less likely to quit or be fired within the first few months.

The key is to let employees know you need good people and specifically what you're looking for. Ask them if they trained with anyone or have worked with anyone in the past who they liked and who might want to change employers.

If you don't already have one, consider implementing a referral incentive or reward program that's fun and creates some excitement. The reward can be as inexpensive as movie tickets or as incentivizing as a generous dollar amount. How much is a great new employee worth to you?