Boys need structure. In partnership with your mentee, develop a schedule, routine or rituals for the length of your formal relationship. Take on his ideas and work as a team to keep on track.
Help your mentee cultivate a passion. Most young men need some kind of anchor-a sport, music, or hobby-that they can turn to when life gets stressful, so in your early interactions, try to figure out what that passion is (or could be), and pursue it.
Play games, go bowling, go to the movies, etc. Give the teen you're mentoring a voice and choice in deciding on activities–it demonstrates you trust them, and it helps build their skills and confidence. And, when possible and appropriate, try and do something active. Movement stimulates the brain to process emotions, and even something as low-key as walking can facilitate conversation.
Asking your mentee open questions will help you as a mentor to identify their real needs, values and passions. It's also a great way to get your mentee to think through situations themselves and draw out the consequences of the various choices or courses of action they can take. During these conversations, you can share your wisdom, without making decisions for your mentee. That's their job.
By just listening—not criticizing or judging—you'll develop trust. Respect the trust the young man places in you–show them that you understand and are committed to the relationship. Mentees benefit greatly from the opportunity of having a good mentor listen to them. Allow them to explore their thoughts and ideas openly with you. This will often help them unravel their thinking and gain insights about a situation as they share their concerns with you.
Not all feedback is helpful. A good mentor knows this and will deliver feedback in a way that will help their mentee gain insight to further develop specific qualities or skills. For example, a good mentor will always ask for permission to give feedback before doing so. Giving unwelcome feedback can be detrimental to any mentoring relationship. Instead, explain what you'd like to talk about first and highlight the benefits of doing this.
Being a sounding board is always more empowering for a mentee than advising them what to do. It helps them work through the issue and come to their own conclusions. By doing so, you ultimately help them to learn to think through issues themselves and trust their own judgement, both valuable life skills.
Good mentors are respected by their mentees. A mentee can learn a lot from his mentor simply by watching how his mentor behaves in any particular situation, so it's important that you're acting like your best self around them. No cursing, no negativity, no second-guessing.
Take responsibility for making and maintaining contact and don't expect too much feedback from the teenager. (He is, remember, a teenager.)