Intervene at an early stage. The longer you allow the child to misbehave, the more the bad behavior will escalate and the harder it will be for you to prevent it. Children will always test how far they can push the boundaries and will only stop when you will make them.
Notify the parents. Children need consistency, and it is important parents know how their child is behaving in preschool. Make sure the parents agree with you disciplining the child and encourage them to do the same at home. If you will get no support from the parents, it will be hard for you to control the child.
Compliment the child when they behave correctly. It's not only about punishing a child; you should also let her know when she is behaving in the desired way. Voice your approval as much as your disapproval, and reward all positive efforts. The reward can be in form of a treat or just a clear expression that the child made you happy by listening to you.
Avoid physical punishment. Hitting the child won't solve any problems. The child will behave only because he or she will be frightened of physical pain. Studies have shown that hitting a child can bring on the condition known as displaced anger, which can present itself as outbursts of aggression later on.
Voice your expectations clearly and set firm limits. Be fair, consistent and strict. If you punish the child with the revoking of something the child enjoys, make sure it is clear to him what exactly brought the punishment on. Never back down from the punishment or the child will think your word doesn't matter.