1. There are going to be things you regret. Period. You will blow it, lose your temper, shirk your responsibility, shrug them off until tomorrow, hurt their feelings or make them feel bad about themselves. In short, you will sin against them not matter how hard you try not to.
2. You are not your mother. That could be good or bad. Perhaps you spent your childhood watching your mother slip deeper into mental illness. Perhaps your mother was infinitely patient and gentle. You are not her. Move on.
3. It's not personal; it's business. This Godfather quote is very appropriate. Your toddler isn't refusing to eat his food to piss you off. It's his job to decide what he likes and hates. He's handling that responsibility badly, but it's not got a thing in the world to do with you. Same goes with cleaning rooms, finding shoes, potty training, etc.
4. A good spanking is infinitely better than humiliation and shaming. They will forget the means of discipline if it is accompanied with love.
5. Stop. Stop what you are doing and make eye contact. That 60 seconds out of your day to stoop down, make eye contact and explain your expectations will make a lot of difference. To not do it will cost you more in the long run.
6. Pursue their hearts, not their behavior. Why is he having a meltdown? Why is she refusing to make eye contact? Why is he arguing? Any number of issues come to light when you pursue the heart. Maybe he's made an idol of those video games and needs you to step in between him and his idol, even though he'll get angry. Maybe she feels like you're not really listening to her, so why should she listen to you. When you want to kick them to the curb, stop and take a deep breath. Say a prayer and then dive into the murky water that is the soul of your child. Attempt to turn them towards the light.
7. Pray. Pray. Pray. Repent. Repent. Repent. Pray for their hearts, for their understanding, for them to see their sin. Repent of your impatience, your selfishness, your false identities, your pride.
8. Believe. Believe. Believe. That God loves them more than you can imagine. That He works in them. That He saves them, not you. That He is patient with you, and that gives you the grace to be patient with them.
9. Enjoy them. Watch them. Never choose sleep over a conversation. Be their biggest fan.
10. They are themselves, not reflections of you. They are people, just like you are people. They have aversions, pet peeves, guilty pleasures, and individual thought processes. Preteens especially crave to be valued for themselves. Stop trying to change them. That sweet boy that you tried desperately to indoctrinate and make love classical music may just like dubstep better. That's okay. It doesn't mean you have failed. It means he's his own person... with bad taste in music. (I kid.)
All of these things can be summed up in one: Love them. Love them, for themselves, not for how they reflect on you. Open your heart to them. Pour your energy into them. Adore them. Be their champion. And go back and read number 1 again.