Here is a strategy that worked for me and has turned my band around.
I focused on the one sweet Mormon girl who was polite, smiled at me and said good morning, and answered questions in class. When I spoke with the band, I pretended I was talking to just her. When I was being super positive and nice (hyper-focusing on her in my mind, but speaking like that to everyone in band), the kids began to like me more.
Eventually the band ended up turning on the two boys in band that liked to be stupid. Not yelling or anything, but whispering "stop!" or rolling their eyes. It became uncool to be an idiot in my class.
This is year nine. Every year I find that ONE kid, and it expands out.