"Maintain high standards of ethics and professionalism: Mentors and mentees must strive to uphold appropriate ethical behavior as professionals." 

Best practices for ethics and professionalism in a mentoring realtionship:

• Promote mutual respect and trust
• Maintain confidentiality
• Be diligent in providing knowledge, wisdom, and developmental support
• Carefully frame advice and feedback so it is well-received and constructive

From Amy Greil's "A Story of Mentoring" found online at http://www.kenoshanews.com/news/amy_greil_a_story_of_mentoring_493097750.php

As a mentor, it's a good idea to maintain a professional image for your mentee. Especially in workplace based mentoring relationships, a mentee will often view the mentor as a blueprint for achieving sucess. Mentors can use their own professional accomplishments and career to help guide their protégé towards acheiving their goals.