The negative approach involves punishing a child whenever be displays undesirable behavior. Positive approach consists of rewarding a child whenever he behaves well but ignoring bad behavior.
The positive approach should be used much more frequently then negative approach. Children always want attention and by focusing on bad behavior we indirectly encourage it.
Anyone carefully observing children can notice that any act, which draws the attention of people around will be repeated. In fact this is true for adults also.