I recently did a parenting course called "Parent Effectiveness Training". I learned an awful lot. If it's available in your area, I would DEFINITELY recommend it.

It teaches you techniques for identifying problem behaviour, identifying who is responsible for the problem ,and techniques for dealing with the behaviour. The child needs to be told what the problem behaviour is, what the tangible effect on you is (ie money, effort, energy) and how you feel about it. You need to listen to the child and make sure they understand that their behaviour is causing YOU problems and if they change their behaviour, then you'll be happier.

For example: DS2 is kicking the back of the driver's seat in the car. I say "DS2, when you kick the back of my seat, I get worried that we're going to have a crash".

another example: DS1 is hitting his brother. I say "DS1, when you hit your brother, he cries, and I have to comfort him, which means I don't get time to make dinner/play games with you/read my paper in peace". Whatever is appropriate for the situation.

HTH.