Good assessment is systematic in that it is a planned and regular process. This brief IDEA Paper by Susan Hatfield is an excellent introduction to assessment.
You can also view examples of other ISU assessment plans on the Program Assessment page. The nature of the education process, however, also lends itself to discovery. A good plan should be open to discovering new ideas and emerging themes.
Good assessment should be meaningful in that it addresses questions that you care about. Program evaluation and assessment should be a collaborative, inclusive and open process.