Don't worry every child has their day, not every child is perfect. I have a 4 yr old myself and what has worked for me was the advice from the tv show Nanny 911 and Super Nanny. You can purchase their book as well at any bookstore. My husband and I will put him aside for time out even if we are at a restaurant, he gets so embarrassed and it works. You have to correct her right there and then as camly as possible. Explain to her what she is doing wrong and that its unacceptable behavior. Praise her everytime she is behaving well. If your out shopping, you can let her pick out something to play with before you start shopping, and let her know that its just for her to play with and that you will put it back in the shelf. If the time out doesn't work, you can always take all her toys ( or any special things she likes to do) away, and she can only recieve them after good behavior.