I had the opportunity to experience mentoring in my company. First as a mentee and then as a mentor.
So I had a vision of both and created a guide for my department to develop mentoring.
I contacted an employee from marketing department because I wanted to have advice about his job and develop compentencies. Then myself I shared my experience of this as a mentor.
Did you know "Mentor" is a proper noun indicating Ulysse’s friend; responsible for the education of his son Telemachus during his absence in the Trojan War according the greek mythology. The word mentor then mean a wise and experienced counselor.
So 2 key points : Sharing experience and developing knowledge.
There's a lot fo mentorship programs all throughout schools and extracurricular activities. To become one, try to join a club in an idea that interests you. It could be anything from a robotics club, to chess, to even a fraternity, and then apply for their mentorship programs to help an underclassmen student who was just like you.