Being a single parent for many years forced me to be both mother and father. And without child support, I had to work long hours and multiple jobs. I learned right away that the only way to have any kind of control over our lives, I had to demand respect and stand firm. Therefore, my one tip would be: Be a parent, not a friend.
You can always be their friend when they get older but in order for them to grow into self sustaining and law abiding adults who respect their teachers, their caregivers, or anyone in authority, that has to begin at home.