I've never been comfortable with performance reviews. I've always had fairly positive reviews, so it's not that I've been subject to harsh criticism. There's just something about sitting there under the microscope that just makes me anxious. Also, I don't like being in the position of "Marketer of Myself." I know that goes against the very grain of Career 101, but I can't help it. What I've found that helps me is going in prepared with my own self-evaluation. That way, I'm armed with facts that the boss and I can look at and avoid the discomfort of generalizing my worth.
Even if your company doesn't require a self-evaluation, it's a good idea to do one anyway. List your accomplishments during the year. (Click here to download a free Accomplishments tracker template.) Even managers with the best of intentions often don't have the bandwidth to keep track of everything you do. That’s your job.
Your mission, basically, is to outline why you are valuable to the company. It's best to steer clear of general and far-reaching statements. In other words, you don't want to say "The world is a better place with me in it." While that may be true, it's not the kind of thing that fits in a performance review. If you think, on the other hand, the company is a better place with you in it, then think of two or three reasons that's true.
You can't illustrate your contributions with broad statements like, "successfully managed two projects." You need to describe the projects you worked on and you need to define what "success" means in the sense you're using it. Did you come in under budget? Did you save the company money? The more specific you are with the numbers, the easier it is to monetize your contribution. It sounds cold to equate your worth as an employee by how much money you make for, or save, the company, but numbers aren't subjective and the bottom line is the bottom line.
This is not to say that you can't talk about contributions that are less quantifiable. But even those need to be illustrated. If you think you've played an informal leadership role on your team, then say so and describe an instance in which this was true. If you personally believe you've incited your fellow team members to greater productivity because you play Gregorian Chants very loudly from the stereo on your desk, you might want to keep that to yourself.
It is also in your best interest to define, with your manager, your future goals as specifically as possible. While it may be easier to list as a goal "Learn more about VoIP," you need to identify specific activities that will allow you to do this, like taking seminars or classes. This will also make it easier in your next review, to point at those activities you've completed.