What does it mean to be a relational teacher?  If you had asked me when I was younger, I think I would have had the mistaken belief that being relational as a teacher meant being a friend to your students.  Having lived life long enough to have some experience in working with kids, and adults for that matter, I think that it is more complicated than that.
On some level, it is a kind of friendship.  But, you would make a mistake to equate it to the friendship of a peer.
My first job at a management level, where I needed to be responsible for my own department, taught me that you absolutely have to connect with people; but you should take care in how you go about this.  I had to go out of the office quite a bit, and decided that since we were all adults, I could trust my unit to behave and follow procedure.  What can I say - naïve.  The hardest working members of the team became incredibly frustrated because those that were not as hard working abused the situation.  I did not assert myself enough to stop this before it created a serious problem.  I had made the mistake of acting like a peer, not the manager.  I had connected with every team member, but not in the way that stated that I was the manager and I would lay down the law . . .  Whoops!
I think that a relational teacher is the same sort of thing.  You get to know your students.  You invest time in trying to find out what is important to them and what you can do to help them knock down barriers.  You care, but as the teacher.  You are the guide, not the buddy.
I think that first and foremost, you create a friendly and safe environment.  Greet the kids at the door, let them know you are happy that they are there.  Set the expectation that while there are no dumb questions, there are boundaries -- like they have to respect each other.
I think that you also build them up with small group activities, where they not only learn together, but learn from one another.  I also would tend to ask the kids what they liked as the year progressed, steering the class with input from the students.
The one thing that I have learned from coaching is that kids, especially the teenagers, will let you know exactly what they think - so bottom line is to pay attention, value the feedback, apply lessons learned along the way.