You wouldn't take a trip to an unknown destination without a map or at least a reliable GPS device. Without a map, you might end up spending half the trip retracing your steps as you try wrong road after wrong road. Your career is much like a trip. Without goals, not only will your job performance suffer, you may take many wrong paths before you find your way to success.
Whether you are a manager defining goals for an employee or an employee who is determined to be the best at what you do, define specific job performance goals that are measurable. The more thought you put into pinpointing the goal, the more apt you are to see results. Avoid general statements such as, "Employee will improve accuracy." The statement does not provide enough detail or a way to determine if the goal has been met. Measurable goals provide you with hard numbers that everyone can agree upon as a success. For example, if the goal is to complete Project A under a $1 million budget, the end cost of the project will be proof you succeeded.
The job performance goals need to be realistically achievable and yet challenge you to excel. You can set a goal to do the work of three people in half the time, but realistically, you are setting yourself up to fail. Allow time for other goal accomplishments, as well. If the goals are not achievable, you may be tempted to quit as soon as you miss meeting one or two milestones.
A good goal sets deadlines and milestones along the way so you can measure progress incrementally and tweak the goal as needed. A deadline sets the timeline and clarifies what it takes to be have achieved the goal. Milestones provide periodic opportunities to celebrate successes or analyze the cause of failures. Keep in mind that goals are subject to change as additional responsibilities and priorities complicate your work life.
Job performance goals that are set as a collaborative effort between the supervisor and the employee help to ensure that the both parties are committed to the results and understand what is expected from the employee. Even if you are setting goals for your personal benefit, discussing job expectation with the boss will show how committed you are to succeeding. That way, you also can ensure the goals do not interfere with other priorities your supervisor may have in mind for you.