Graduate students can identify potential faculty mentors within or outside their departments using a variety of formal and informal means.
At a large research university, it can be daunting to approach a potential mentor at first. However, taking the initiative to explore discussions with faculty is a more helpful approach than waiting for them to approach you, especially in disciplines in which graduate students and faculty do not necessarily interact every day. Prospective mentors will appreciate your interest in their work and will be eager to talk to you.
Consider the composition of your informal mentoring team. While it is common to choose potential mentors based on similar experiences and ways of thinking, you also can benefit from individuals whose backgrounds, characteristics, and perspectives are different from your own. Some of the most meaningful mentoring occurs when mentor and student explore different takes on research or teaching problems and yet focus successfully on what matters most: mutual interests and learning from each other. Beyond assessing rapport, inviting individuals of a different ethnicity or gender to serve as your mentors will help you develop a more reflective understanding of your own work and future possibilities.
As you begin to identify prospective mentors, look for a balance of senior and junior faculty members. Each can be of assistance, although possibly in different ways. Senior faculty, because they have been in the field for a long time, may be able to help you better with networking. Junior faculty, having been in graduate school relatively recently themselves, may be able to help you cope better with the stresses and strains associated with being a graduate student.
Finally, seek potential mentors outside your department, or even outside the university, whose intellectual or professional interests relate to yours. These individuals will not only be able to provide you with a fresh perspective on the nature of your work, but can help you understand how it relates to exciting questions or practical problems in other disciplines or professional fields.