teaching - What is the best way to keep your students from getting out of control?

I am new to teaching. Recently I was given the opportunity to teach at my own university (I am currently doing an MPhil from my university). If a teacher fails to control his students once, he wouldn't be able to control them until the end of semester.

This is my first time in teaching and I am afraid that my students would get out of my control. They wouldn't listen to me, would misbehave and wouldn't let me give my lecture without interruption.

Please advise me the best way to keep my cool and prevent my students from getting out of control.

EDIT: I have not started teaching yet. I'll be starting my classes from next week.

EDIT2: The students are Bachelors students. I don't actually want to control them. I just want to maintain discipline in my class. I want to prevent misbehavior in my class. I have seen students not listening to new teachers and just pass the whole lecture passing comments.