To me, the classroom environment centers around mutual respect. In my years as a teacher I have been to many required trainings on classroom management, but the simplest thing continues to be my best weapon in preventing and dealing with discipline issues: I treat my students with respect and demand it in return.
I wish students entered my classroom with an innate sense of respect for me (and some do), but the roles of children and adults have changed since I attended school. When I grew up, the teacher was alway right. Today, many parents try to befriend their children and their relationships are based more on friendship than respect. If a student doesn't respect their parents, how can I expect them to enter my classroom and respect me?
I model respect to my students, and show it to them first. I treat them as wish to be treated as an adult, even though they are students, and I explain it to them when I am doing it. I look for opportunities to treat them better that they expect me to, and to show them greater respect than they are accustomed. By laying the foundation of respect initially, I have platform from which to handle discipline problems.
I make my expectations for behavior clear, but when a student gets out of line I never yell or punish a student in front of the class. In a private conversation with the child my first question isn't to ask them about what they did wrong, my first question is to ask the student if they are ok. Many times the student isn't frustrated with me or my class, rather some outside problem. Instead of taking a personal insult I determined the problem, showed that I was concerned, and ask if I could be of help. I still explain that their behavior was innappropriate and it can't continue, but most students immediately change their actions after this type of exchange.
If a private conversation ever turns hostile from a student, I continue to remain calm and firm and never argue with a student. If you argue with a student, they win immediately because you have lowered yourself to a peer rather than a superior. Of course, talking to parents can be a help, as well as administrators, but in my years of teaching I have only had to send a handful of students to the principal for assistance. I firmly believe that if you treat students as adults and respectfully set expectations that most classrooms will have a positive environment.