If you mentor as part of a program, it’s likely that a supporting process and principles are already available to you. The amount of structure used in mentoring programs varies: most appoint coordinators to match mentees to mentors, while some encourage mentees to find and approach their own mentors.
Some programs have formal reviews and assessment mechanisms, such as structured interviews or electronic questionnaires, while others are happy to gather anecdotal feedback as an indication of effective relationships. In organizations, potential mentees are often people identified as talent/high potential or requiring development.