Jesus so often started discipleship with the words, "Come to me," or "Come follow me." He didn't tell them everything they needed to know and do. Discipleship was just the invitation to join him and learn along the way.
While we're not Jesus, we can say confidently like Paul did, "Follow me, as I follow Christ." Some the best discipleship you can offer a friend, is simply to invite them to join you in what you're already doing as a growing disciple of Jesus.