If you want improve your classroom management, there are several things that can help you. Being prepared for the first day of school is one of the most important attributes needed for successful classroom management besides being consistent.
Having planned out the course, looked over the textbook, and created your quizzes, tests and assignments will assist in you having a full understanding of the learning objectives and of how the assessments and learning activities correspond to each objective. We also need to have our gradebooks ready by the first day, so we can learn and practice students' names before we meet them. It also assists us in taking roll the first day - why wait until 5 minutes before class to get a class roster?. This will also make learning students quicker, which in turn helps to minimize undesirable behavior in the classroom.
Besides planning for the course, we need to develop a syllabus that describes the course, objectives, policies and procedures, course outline, and a little bit about you. Make sure you go over the syllabus with the class so they know exactly what they will learn, what they need to do to succeed, and how you manage the class. This will be a time for them to raise any questions or concerns they have about the course. The syllabus also helps to re-enforce the policies and procedures of the class and school; incase a situation does arise, you have the syllabus to refer to. This will help you be fair and consistent with each situation.
Furthermore, to help make classroom management easier make sure that you are ready for the first day. Have copies of the syllabus and handouts ready, classroom organized and clean, arrive to class early, meet each student prior to the start of the class (if possible), start your class on time, be dressed appropriately, and set the example from the second the students walk through the door because you are the one the students want to strive to be like. One last thing, don't try to be their friend; instead, be their teacher and help them grow.