When my son began working as a 12-year old den chief, a Boy Scout helping a Cub Scout den, I did not know what to expect. When the meeting was over, I asked him what he thought about it. He said very slowly and deliberately with a pause between each word, “It was like herding cats.”
Many first time den leaders have the same feeling after their first den meeting.
One of the first lesson is that any good den leader can have is how to implement a system that encourages good behavior.
At the website scoutermom.com, she has a wonderful and simple article with some great positive reinforcement mechanisms. Take a look.
Some of these ideas apply equally well to older scouts, too.