Four key skills for effective communication in mentoring relationships are:

Increase your awareness of yourself and others.

You are the instrument through which mentoring happens, both as mentor and mentee.  The more you are clear about your own agenda and able to separate out your own thoughts, feelings, and wants from those of your mentor/mentee, the greater the potential for intentional partnership and mutual benefit.

"In each moment you spend in another person's presence, you are communicating that person's importance to you.  Are you doing this consciously or unconsciously?"  Denise Holmes 

Get curious about the other person's story.

Listening in order to learn something new (rather than to confirm what you already know) is essential to good mentoring.  When you get curious about the other person’s story, you open up the possibility of greater connection and value for both parties.
Read more about barriers to effective communication.

"In order to understand what another person is saying, you must assume that it is true, and try to imagine what it could be true of." George Miller 

Listen for passion and potential.

Great mentoring means understanding what makes the other person tick, what has brought them to this moment in their career, and where they would like to go next.
Read more about active listening.

  "Listening for potential means listening to people as if they have all the tools they need to be successful, and could simply benefit from exploring their thoughts and ideas out loud."  David Rock

Share your own crystallized experience.

One of the pleasures of mentoring is the chance to share one’s own hard-earned experience so that it might be helpful to others coming along a similar path.
Read more about giving and receiving feedback.

"Ecologists tell us that a tree planted in a clearing of an old forest will grow more successfully than one planted in an open field.  The reason, it seems, is that the roots of the forest tree are able to follow the intricate pathways created by former trees and thus imbed themselves more deeply. This literally enables stronger trees to share resources with the weaker so that the whole forest becomes healthier.  Similarly, human beings thrive best when we grow in the presence of those who have gone before."  Parks Daloz

Find more resources on communication.