Establish and maintain eye contact with the child while you are talking. A simple verbal and visual clue such as "eyes right here, please" while touching the bridge of your nose will help establish eye contact. Get down on the child's level before you begin speaking to him.
Use just a few words to explain the misbehavior to the child. Being long-winded can result in the child's tuning out and not listening.
Explain that the behavior that you noticed was unacceptable and tell him that there are consequences for this behavior. For example, say "Hitting your friend is not okay. You will need to sit in time out for three minutes for hitting. Then you will apologize to your friend."
Be consistent. Address each misbehavior as it happens and be sure to handle similar infractions with similar consequences.
Document consistent misbehavior and see if you notice a pattern. If you see that there are many misbehaviors around the same time each day, take a good look at your daily lesson plan. See if you can change the room arrangement, lesson plan or transition plan to minimize the amount of misbehavior in the classroom.
Read through your documentation and decide which steps to take next. If you notice a pattern of misbehavior for a particular child, consider calling the parents and ask for suggestions for dealing with misbehavior with their child. Consider a parent-teacher conference if the behavior continues.