A: One of the best ways to decrease negative behaviors is to increase positive ones. A child can't act good and bad at the same time, so parents should "catch" a child being good and really praise it. Consider using a sticker chart to keep track of the times your child engages in a specific "good" behavior; after a certain number of stickers have accumulated, he gets a reward like a special toy.
There are also ways of saying "no," which will decrease frustration. Give your child choices ("Well, those pants don't match this shirt, but choose one of these three shirts.") or tell him when he can do something ("First we have to clean the room, but then you can watch television."). Additionally, try to avoid situations that lead to bad behavior. For example, if tantrums arise because he doesn't want to stop playing a game to take a bath, set a rule that bath is always taken before playing any games. If he gets upset every time you go to the store and you don't buy him something, consider going to the store when he is at school. If he is tired or hungry, try asking him to clean up after his nap or his snack. And if tantrums get him out of doing something that he doesn't want to do or it gives him something that he wants, he is more likely to continue them. So always make sure that bad behavior don't work out in his favor.