Well, I do think that Kairi has a point. I don't agree with spanking your child every single time that they do something wrong; that really would be abuse. And plus, you don't ever want to hit them whenever they are young. When children are really young, and I'm talking about a few months old, then there's really no way that you can spoil them, because they're totally dependant on you, and you have to take care of them almost all of the time.
Though, once they are older, then yelling at them every time that they do something wrong will not be effective after a while. It may work at first, but sooner or later the child learns that, 'Hey! All she's going to do is yell at me. That isn't hurting me, so I'll just ignore her', etc. Trust me, I've witnessed this, and I know from experience, unfortunately. ~_~ That still doesn't mean that you need to go straight for the belt and pop them, though. I would only say to give them a little, not hard, pop on the hand or something, so they'll learn that no means no. It may seem like abuse, but as long as you don't go over-the-top then they won't be hurt. It says that it's okay in the Bible, as long as you don't abuse your child, but that's just what I go by. I don't resent my mother in any way for spanking me; I think that I probably would have those feelings if all she did was yell, though. Who wants to hear a parent yelling? That's more annoying than a spanking, in my opinion. And really... Unless you teach your child discipline, then they might do something really dangerous, and if they don't have a slight fear of you, just to know that you're the parent and they're the child, then they won't obey you. They'll think they're too good or something.
I know someone who once left her three year old daughter with her grandmother, who can't see, at her apartment one time. After the mother had left, the little girl ended up running out of the front door, and out onto a main, really busy street, and of course this scared her grandmother to death because she couldn't see her. She called for the little girl to come back, but she wouldn't listen. Thankfully, no one ran over her, and a man found the little girl and brought her back over to her grandmother's house.
This just goes to show that you have to get your kids to listen to you, and let them know who is boss. This little girl has only been yelled at, or given time-outs, or something that really didn't bother her too much, and she's learned to not listen to anyone because she knows that they won't do anything to her.