1. Never Hit Your Dog
This seems simple enough, but it's surprising how many people i've seen that will physically hit their dog as a punishment for negative behavior. Not only does this actually do the opposite of what it's meant to, it can make the dog aggressive toward people in general. An aggressive dog is a danger to all around him/her, and if it gets too bad, animal control may be forced to get involved. There is always a better way to reprimand a dog than physical violence.
2. Speak With Authority
Dogs can sense when their owners are weak willed. When giving your pooch commands, speak with a firm, dominant voice and look your pet in the eye to help establish your dominance in the pecking order. It's surprising how much of a difference a dominant, confident voice will make in training or reprimanding a dog. Some dogs misbehave simply because they feel that they are the authority in the house, so they do what they please which we see as mischief.
Attention is an excellent motivator for most, if not all, dogs. Dogs look to their owner for approval with everything they do. Your attention can heavily influence whether or not your dog repeats a behavior whether they receive treats and other rewards or not. When your pooch does a positive or desired behavior, always be sure to give him/her plenty of attention and praise, but on the contrary, if he/she is misbehaving you need to look away and avoid giving them any attention long enough for them to calm down and if necessary use a dominant "No" to stop them in their tracks.
Hopefully these tips will provide some insight to the owners with mischievous or disobedient pooches