Recently I started teaching Asian students in Montreal and was told that kid behavior has changed from the old countries to the new where parental respect was more predominant to begin with. First of all, it is important to solve any annoying issues before the class begins. There are a couple of solutions that can get the support of parents and that is the setting up of an educational funds to provide services or materials for the child. Now parents might disagree with the system especially if this is done after a cost agreement is made with them but then they have to know what the circumstances are especially when you hear of mothers that run off to work unable to discipline their kids.
It helps if you can establish how much the kids have to contribute when they don't do their homework. Extra homework should also be given out so that students learn responsibility. If the student comes in chewing gum and wanting to wear a coat I have let that ride especially when my main objective is getting them to learn and not spend most of my time disciplining them. I have also learned that to sit among them will control some of their passing gum or poking one another. A system can be established to have students compete for best-improved grades and that information would be forwarded to their parents.
I will digress slightly and say that it is ideal to work with a smaller bunch of kids if you can, numbers plays a big role but that doesn't always work. I once had a remedial class in Italy where the kid started to throw chairs around because his Mom and Dad had just separated. It appeared he would have liked to control the situation and was powerless. That he had to make up courses for his Mom, who he must have had an animosity for only aggravated the situation. Then I tried to establish some neutrality saying that his being there had do with low grades and if he would improve them he would make both his parents happy. The corollary was important for him to understand that by being violent he would be annoying both parents and it is important to use positive words when giving advise.