I have no experience with this given I'm currently pregnant with #1, but when I was over at my friends the other night for dinner, she was telling me about the system she has for her DD who is 3. Every night she can earn 3 stickers. 1 for eating all her dinner, 1 for cleaning her toy room and 1 for cleaning her bedroom. Then at the end of the week if she's earnt a certain number of stickers she gets a special present. I think last weeks present was a colouring book.