Some common  behaviour problems which your dog may exhibit:

Pulling on the lead

Lunging at dogs and people

Jumping up at people

Have a fear of noises

Become aggressive

Bark continually

Suffer from anxiety

Bark whilst in the car

Destroy your furniture or possessions

Become obsessive

Refuse to come when called

Toileting in the house

Picking at his/her food

With any behavioural issue, to ensure the cause of the problem is treated, it is important to look at the whole picture, not just the symptoms. 

I use only natural methods.