In case it's useful to anyone, attached is a handout that I drafted to distribute to the student boards of departments at our university to guide them in their evaluations of teaching.  (At our university, each department has a student board that evaluates faculty in their department, in addition to the regular student evaluations.)  The handout offers practical guidelines for limiting bias.  I will also be giving a presentation to the student boards that is more conceptual and designed to help them appreciate the pervasive and unconscious character of bias, and thus the need to take extra steps to limit bias.  The handout is more specific and practical-oriented.  (The sources at the end are still a bit unorganized but they are all there.)