Let your people know where they fit in, how valued their pesonal contributions are, and what is expected of them. Stay abreast of your competition, their pay scales, their benefits, and new, emerging trends. Reward results, not tenure. Recognize people for what they do, not for their longevity. Give special awards for special contributions when they happen, not at the end of the year.
Workers get bored when they stop learning.
Invest in all of your resources you wish to retain and you will reap the return. Reveal growth opportunities. Workers lose interest whenever they feel stymied in their careers. Show them what jobs they can aspire to and how to prepare themselves. Identify your stars and worship them.