By Margaret Steen, Yahoo! HotJobs

The No. 1 piece of advice for managers getting ready for their employees' performance reviews? Allow plenty of time.

"Everybody hates it," says Diane Foster, principal of executive coaching and consulting firm Diane Foster & Associates in Alameda, California. "Nobody really wants to prepare their workers' reviews." But there's a price to pay for managers who breeze through the preparations, then just try to make it through the employee meetings without hurting anyone's feelings. "Too many people leave the performance review without having a solid understanding of what the boss really wants," she says.

Helping your employees do their jobs better is one of the most important parts of a manager's job. So it's critical to think through not only what you're going to say to your employees, but also how you're going to say it.

Experts offer these tips for getting through your performance reviews and making them useful for you and your employees:

"Talk about the performance, not the person," suggests Meryl Runion, author of How to Say It Performance Reviews. "Instead of saying, 'You're not doing your job,' say 'Your performance is not up to standards.'"

Be specific. This is easiest for measurable goals: You were expected to sell 100 pairs of shoes but you sold only 80.

Carol Gegner, principal of Executive Coaching and Consulting Systems in Walnut Creek, California, adds that it's important to explain how the poor performance is affecting the organization. "Then you need to be able to describe the change that you'd like to see," she says.

Also be specific about what your employees are doing right, Runion adds. "Don't just say, 'Great job.' Say, 'Great job. Here's an example of a time when we knew we could count on you,'" she says.

Review your employee evaluations with your own manager before you deliver them. At many companies, doing so is required. But even if it isn't, it's a good idea to make sure your own biases haven't influenced your ratings. "We all have individual personalities," says Glenn Shepard, a management consultant and owner of Glenn Shepard Seminars. "We sometimes are not as objective as we should be."

Watch out for what Shepard calls "recency bias." If you do performance reviews once a year, you're most likely to focus on what the employee did in the month or two before the review. This can lead to a bad review for a worker who had a good year with one problematic project at the end -- or a better-than-deserved review for someone who started working hard only when review time was approaching.

Focus on a few key messages for your employee, rather than a laundry list of accomplishments and problems. "If you don't prioritize, the problem is that the listener may be overloaded and miss the most important points," Foster says.

Make performance management a year-round process. "Someone who's good should know they're going to get a good review, and someone who's awful should know they're going to get an awful review," Shepard says. "If it's really a surprise, that screams poor management."