Post these rules in the room and review them periodically. Norms established by the group are more likely to be respected. Don't look for miracles to happen overnight. If a student has a history of misbehavior and maladjustment over a period of years, nothing the teacher can do will change the student completely overnight. Don't be discouraged when, after a period of improvement, the student with problems suddenly regresses.
Physical proximity is the best tool.
Moving throughout the classroom is an excellent deterrent to misbehavior. Be consistent when applying the discipline plan. Don't argue with a student in front of the class. By doing so, the student has been made an equal before an audience that may side with the student. Strive to help students develop self discipline.