I believe that a successful form of behavior management is one that is uniform accross as many levels of the childrens' lives as possible. As a teacher, I have found that the most successful forms of behavior management are those that all teachers follow through on, and which administrators also practice and back up. This way, the students do not think they can get away with different things in different environments or around different adults.
That being said, my advice to you would be to contact the school that most of the children you drive attend. Ask if you can have a copy of their school rules or behavior contract. Also, inquire about their consequences for negative student actions. Then, take a look at these rules and see if you can implement them in any way on your school bus.
The other thing I would offer is to make sure the rules and consequences are clearly posted on the bus, so the kids know what is expected of them and are reminded of the consequences of negative actions.
Several of the districts I am familiar with have Bus Aides ride the bus with the students, some have installed cameras as well. It is difficult for one bus driver, who needs to be paying attention to driving his precious cargo around, to also regulate everything that is going on in a crowded bus. I think having a bus aid is a great idea, with a driver up front and a bus aid paying attention to everything going on amongst the students, the students will be much safer -- that way the driver can concentrate on driving and the bus aid is there to protect and help students, and control behaviors to make it safer for the driver to concentrate.
My district has cameras on all the buses, and we haven't had any major discipline problems that I've heard of. We also have a strict conduct code. In a neighboring county, cameras on the bus didn't prevent a rape from happening. A high school senior pulled a middle school girl onto his lap and raped her on a crowded bus; even though she screamed for help, the bus driver says he didn't hear her, and the other kids didn't help. Now that county requires another adult rider on each bus.
That's the question of the year in many places. When you've got kids on a bus for an hour, with just a driver, all sorts of REALLY bad stuff can happen. Putting a video camera on helps after the fact, but other than allowing you to figure out what has already happened, isn't the best option, in my opinion. We have had to put a second adult on buses in several instances, because there is only so much a driver piloting a bus down a highway can do. Assigned seats can help, when you have chronic offenders. Positive reinforcement of good behavior helps with some kids. A bus driver who forms a good relationship with the kids from day one, helps, as well.
My school has recentally installed two cameras on all 6 buses. They are in the front of the bus and in the back off the bus. We also have an aide ride on the bus that monitors what going on.