The reason most bosses have trouble with the evaluation process is that they see it as a once or twice a year administrative process instead of the core of supervisory leadership.
One way you know that you've had a successful performance evaluation is that no one is surprised. You achieve that by making discussion of performance and behavior a part of day to day management.
Do lots of small, informal course corrections with your people. These should happen during the course of every day, in the cracks in the system, if you will.
Make a clear transition from these informal supervisory interviews to more formal, documented ones. Let people know that you're paying attention. Let them know what behavior concerns you. Let them know what you expect.
Use longer, documented supervisory interviews to help folks improve performance or correct behavior.
For years I've studied top supervisors, those nominated as such by their bosses, their peers and their subordinates. I call them my Three Star Supervisors. In one study we found that Three Star Supervisors do two things differently from their less effective peers in their organization's performance evaluation process.
The most obvious things was that they took longer. Less effective supervisors averaged around ten minutes for the performance evaluation interview. Three Star Supervisors averaged twenty-seven minutes.
Not only that, the content of their interviews was very different. The shorter interviews used the organizational form as the centerpiece and paid most attention to behavior during the evaluation period. But Three Star Supervisors spent their time talking about the future, how things would be different, how they could help the subordinate achieve his or her goals.