Sorry me again...heres a few things I have done with my little boy
If he his naughty he gets sent to the naughty step at the bottom of the stairs which he as to stay on for 5 minutes or until he as calmed down, if he is naughty again he gets put on the top step of the stairs and he gets to stay there for longer, If he takes it upon him self to be naughty again then his next step is to be put in bed with no tv and he is not allowed to play with his toys, I think this works for my son as he very rarely as to go to the top step and never gets put to bed, he is 3 like your girl but he still seemed to pick up on this very quickly and now thinks twice about keep being naughty as he doesnt want to end up in bed.
I also use treats as rewards and here are a few very cheap ones
I bought a badge with his favourite character on and if he is being a good boy he gets to keep it on, as soon as he is naughty i take it off him, little reminders thruoghout the day help him to remember to be good or he will lose his badge. You could make you own badges.
In boots they sell bath tablets which change the colour of your bath water and they are only �2 for 20, if he as been good i let him have one in his bath at night and he thinks its brilliant, Food colouring would do the same trick.
I also have a box of toys that i call the goody box, they are basically toys that he needs assitance with, theses toys are only got out when he as been very good then i sit and play with them with him.
Last but not least i use painting, doing crafts, baking as rewards for good behaiour.
hope this helps