It all starts with the understanding that they’re the children and you’re the adult, and although I love them with all of my heart, I am in charge of them. You set clear boundaries and enforce and reinforce them. As far as how boundaries are enforced and reinforced, it depends which kid, what they’ve done, and what has or hasn’t worked already. The biggest things are consistency and following through on your promises so they know to believe you when you say you’re going to do something. Whether you tell them you’re going to reward them or punish them, do it. It lets them know what to expect and makes it easier to deal with momentary bad behavior.