Need help writing an employee performance review?

As an NCO in the Air Force one thing I learned was to keep it simple and truthfull. BS and flowery phrases don't mean a thing and don't do you or the employee any good. 

What you should be writing are facts and specific achievements of the employee. He/She is great is neither a fact nor a specific achievement. 

He/She accomplishes his/her tasks in a timely and efficient manner could be a fact if they do so. If they show initiative in getting work done rather than waiting around for someone to tell them what needs doing that should also be shown. 

If, on the other hand they sit around until being told to do something that should be stated. Basically the review should be how well they perform, how well they met set goals and whether or not they need to improve certain aspects of their work.