Use positive reinforcement in the classroom. Positive reinforcement will encourage a certain behavior to continue and will increase it. After you get the behavior you are seeking from your students, reward them. For example, if you are having trouble getting your students to turn in homework, until your students are conditioned, reward those students who do turn in the homework with homework passes, candy or movie passes.
Negative reinforcement is another way to produce a desirable behavior. In this case, students behave a certain way in order to avoid an action from happening. As a teacher your best resource is already available to you from day one -- the parents. Parents are useful in helping you to manage your class. For example, tell students that if they want to avoid having their parents called, then they do their work. In order for this to work, you must follow through, and you must call parents if this is the method you chose.
Positive punishment is punishment that includes an added "negative" element. It doesn't necessarily mean that the punishment is happy or that it is preferable to negative punishment, just that it has an added element. For example, if students fail your midterm, you then in turn call their parents, and the parents scold their child. In this example, "scolding" serves as the negative element.
With negative punishment, you as the teacher will have to take something away from your students that they like or enjoy in order for you to get your desired behavior. For example, if your students are constantly complaining about the assignments that you give them for homework, take away a student's homework pass or video pass.