A mentor is critical to your success as graduate student and professional. The professional role to which you aspire entails multiple facets. No one mentor or advisor can provide the breadth of guidance and advice that you will need. Instead, InsideHigherEd's Owen Sutkowski explains that you should cultivate a kitchen cabinet of mentors who each provide different kinds of assistance: the friend, the role model, the insider, the veteran, and the teacher.
Also see: Advisor Check: Real vs. Ideal