I first started using a reward chart with DD at about 3. It was basically 5 things that she needed to do each day - I changed them over time though. Things like - say 'ok mummy' when asked to do something - use you're manners - brush teeth after breakfast and dinner - make sure all clothes are in the washing basket - and smile when saying goodnight to mummy (instead of screaming the house down lol)

I found that it did work quite well, I would always start to forget if it was just you'll get a sticker for doing the right thing. Its much easier to reward if you know what you are looking for. So if DD got a smilie face for each day of the week then she would get a sticker at the end - at least 3 out of 5 stickers at the end and she got to pick something out of the prize box (which is just dodgy cheap things I see when I am doing groceries, like stickers or plastic jewellary, etc) - if she got 5/5 I would let her pick something next time we were out.

I recently changed the system for DD this year (she is 5 now) so that is matched in better with how the school rewards the kids - basically now we have a happy page and a sad page on the fridge - and a prize box. She needs 5 stickers on the happy page to get a prize - but she only gets a sticker for doing something that isnt already expected of her (like tidying her room herself, or still talking properly even when she wants to start chucking a wobbly). When she gets 10 stickers on the sad face - which can be for being rude, not following the rules, etc - I get to pick something of hers that she already has and put it in the prize box - and there is stays until she gets enough stickers to get it out again. Seems to be working a charm!

I hope that helped!