What about rewarding good behaviour, focusing on "catching her being good". Think of something you know she would really enjoy, like going somewhere special, and have her earn it with good behaviour. I have a 3 year old dcb that I am doing this for right now. I made up a small poster with pictures that depict the expected behaviours (for him it is listening the first time and behaving properly when his mom drops him off and picks him up) and then a sticker chart. Every time he earns 10 stickers he gets a reward, so far it has been going sledding with his mom and playing my x-box kinect. He also gets lots of praise too. The long term plan is that his good behaviour will become internalized and the sticker chart will be phased out.

It has been working really well so far, having the reward chart as a reminder of how to behave has really curbed his behaviour so far.