Dear God: HELP!!! (DISCIPLINE)

When I was a teenager, I battled depression, drugs and alcohol. I finally went to a treatment program when I was 19. It was called a "TC" - therapeutic community in Upstate NY, where I was born and raised. I was there a year when my parents and sister decided to move to Florida. I was crushed. Devastated, actually. I felt abandoned yet again.
Growing up, my father and I did not see eye to eye on anything. We fought constantly. I rebelled consistently. He drank, got arrested, was not in the picture at all sometimes. My father is "old school" and is fond of saying, "I call a spade a spade," or, "I call 'em like I see 'em." Yelling, name calling, threats and the withholding of love were common discipline methods.
I am a lot more like my mother than my father. Especially when it comes to discipline. My mother, I think, in a lot of ways (consciously or subconsciously) overcompensated for my father's harsh methods by being extremely lenient; she was a bit of an "enabler", if you will.
With the breakup of my first honest to God true love, I was left holding the baby. Literally. I I devised a plan: go back to school, work, get us a car, an apt, take a crash course in childcare 101: aka; changing diapers, burping, etc. What I did not think of, however, was a discipline plan. I loved this baby; this flesh of my flesh; blood of my blood. I was naive enough to think that love would solve everything. I praised him when he obeyed, listened and/or overcame a milestone(taking his first step, using the potty, etc.) encouraged him constantly, read him stories nightly, cuddled daily, nurtured him consistently. Everyone said what a great Mom I was!
Then, when this sweet little child turned 2, he started talking back. And one of the first words he talked back with was "no." Then, he had the audacity to develop his own opinions about stuff! He didn't like broccoli, when for over a year he had been eating it from a Gerber baby jar just fine. He also didn't like it when it was time to leave the park. He wanted to stay. He didn't want to sit in the shopping cart when we went grocery shopping. He wanted to wander around and look at stuff. Okay, I handled it. I told him he would get his dessert if he took at least 3 bites of vegetables. I told him the park would be waiting bright and early for him to come back tomorrow but right now the park needed to get some rest. He bought it: hook, line and sinker. I told him if he listens to Mommy and sits in the cart, when Mommy's done shopping we can go to the (park!), etc. etc.
And now I have another child. There are days when I yell too much. There are days when I know I've made my children feel "stupid," even though I didn't actually say the word! There are days when I have to pick and choose my battles because it's just, one of those days. Children have "one of those days" too, just like us.
So I guess what I'm trying to say is: don't sweat the small stuff. Take care of the important things (food, shelter) and let God handle the rest.
My ten year old loves art but there are times when he hates his school (and me) for making him go there because the standards are much higher there then at mainstream public schools. He has to do the work. Imagine that.
We are doing this job ourselves. We're going to have good days and bad days. The most important thing is let your children know you love them.
I know what not to do. I'm still learning what TO do and the only way I, you or anyone is going to learn is through trial and error. Don't sweat the small stuff and and leave the rest to God!