Quite a lot has been said about mentoring, and I won't repeat the many facets that make it such a crucial activity. Instead, I will focus on only two facets that serve as my main compass points.
First, one must understand that the subtlest and most effective mentoring often takes place through example. So, it is essential that a mentor be the best scientist he or she can be. A good mentor must strive to publish creative, well-written contributions in peer-reviewed media. Students are keen to learn details of the craft that will give them the power to make discoveries, and they intuitively are exacting critics.
A good mentor must maintain productive, vibrant collaborations. Modern science is very much a social activity. Students want to be successful, contributing members of their science community. A good mentor must value professional ethics and consider the social merits and contributions made by the discipline.
I've found that students often are very aware of the potential influences of personal politics in science, if not the institutional politics and potential compromises they may face. Honest discussions and clear advocacy of values can do much to foster trust, add meaning, and pique motivation. To be a good mentor, therefore, one must not ignore one's own professional disposition.
The second crucial aspect of mentoring is what I refer to as "deep listening": Mentors must know well those whom they advise. One might mistakenly construe the passage above, on professional disposition, as a claim that the best mentoring takes place solely by students emulating a senior faculty member. Nothing of the sort is implied. Students are on a journey to discover who they are and what they can become. Along the way, they pick up impressions of ways to be and approaches that they can adapt, but thoughtless imitation ultimately would hobble them.
The mentor must listen patiently and deeply enough to understand a student's talents and motivation, so that he or she can facilitate growth. This is not a process of blind encouragement and positive affirmation, but rather of guidance stemming from a compassionate understanding of the students' and one's own experiences.
Whether considering my students or myself, I have found that professional development has always been accompanied and served by personal development. Thus, helping students find their own way has been for me the natural complement to finding my path in the world of science.
Carlos Robles is in the Department of Biological Sciences at California State University, Los Angeles, where he also serves as program director for CEA-CREST. During the 2001 SACNAS National Conference, Robles received the SACNAS Undergraduate Mentor Award for his efforts. Robles can be reached at firstname.lastname@example.org  .