I have recently started my 5th year teaching middle school. The only thing I can add to what has already been said, especially because you're teaching high school, is that respect is a two-way street. I rarely have the discipline problems other teachers tend to have and I think that is because my students know I respect them and am on their "team." Even if I reprimand them for an action, I don't hold grudges. Every day is a new beginning. I am their biggest supporter and fan, no matter what level they are at, and every achievement is celebrated. Two things students are not allowed to say in my room: "It's not fair" and "It's too hard." Fairness is a matter of perspective and nothing is too hard - it's a challenge! My students know I wouldn't ask anything of them I didn't think they were capable of. I have helped "problem" students go from an F to a B or A simply by believing in them and taking that little bit of extra time to work with them.
In today's world, some students have no consistency in their lives except for their teachers. I recently heard from one of my former students who I taught my first year. She is now entering her senior year of high school (I am so old) and she thanked me for being the first person who believed in her and told her how smart she was. She came from a not-so-great home life and was told she shouldn't even think about college because no one else in her family had every gone. She became a straight A student, is looking at colleges, and is on her way to what I assume will be great things!! I know it wasn't all my doing, but I'm proud to think I played a small part when she was in my eighth grade class.