I don't let her do whatever she wants. If she asked for candy for breakfast, it's No. It will always be no. But, I don't scream and yell at her. As parents, we model behavior for our children. If I were a screamer, she'd be a screamer, too. They learn to communicate by watching us. I only have one, because I chose to have one. I want her to go to college and have everything she needs. If I had more than 1, I'm not sure I could afford college for all of them. If you watch Dr. Phil, Nanny 911, and Shalom in the Home, you'll see that the bad behavior comes from the parents modelling it. It's hard for parents to admit that it's them and not the kids. I'm not saying being a parent is easy, but some people get frustrated and take it out on their kids. They're just kids. I see my daughter as a little person, and I let her help me with everything. I have days where I spend hours on Math homework. She sits next to me and colors or plays with playdough. She says she is doing her homework, too. If she says she's hungry while I'm in the middle of a tough problem, I just tell her I'll get it when I'm finished. Because I'm laid back and even tempered, so is she. But, that's my personality. I've never been one to stress out even when my fiance and I both lost our jobs on the same day!
My first grade teacher used to make us do that , I cant imagine what parents would do to a teacher that tried to pull that now.
but both of your post sounds slightly "holier than thou" I do agree though that Nanny 911 has some great ideas that do work and I totally agree with alot of what Dr. Phil has to say.
But in the end, you are still the hero. Even if you screw up on occasion! 

No need to mention that....
...didn't think that would have to happen this early.
I never had any problems with her until she started Kindergarten though.