How do you handle discipline with your 4 year old? Time outs don't faze her, and I've taken all of her toys away. She talks back regularly and is generally disrespectful. When it's just her and I, she's sweet and well behaved. Other people come around and she acts out. I've become a yeller and I hate it. I taped a piece of paper up and gave her a sad face, and that seems to affect her and works for the time being, but it won't last. I take discipline seriously and don't like arbitrary punishments, but I just don't know what else to do. Any advice?
P.S. Please don't suggest spanking. I'm not necessarily against it, but I can't use it as a form of punishment in this case.