With a large family, it's important for each child to have his own identity, even though it might be tempting to think of them collectively as "the kids."
Whether you use hooks, drawers or boxes, give each child their own space to put their personal belongings. Let them have their own style with regard to clothes.
Each week, have one child be the designated helper. They can help with the meals, bring in the mail and decide what activities you'll all do. This will eliminate arguing time because each will know their turn is coming.
Also, spend some one-on-one time with each child. Make it official by putting it on the calendar. This will be your time together to read books, play games or just talk. Or she can be the child you decide to take to the supermarket that week.
The logistics of a large family will prevent the kids from getting involved in a lot of extracurricular activities. Let each child choose one, and only one, activity. Whether it is gymnastics, swimming or soccer, this one activity will help them focus on what they really like and who they are as an individual -- and not overburden you with carpool duty.