We started a sticker chart and put on it the behaviors that we want to see as opposed to what we don't want to see. We change this on Sunday's based on what we have seen the past week.
Example of our current chart:
-Do what is asked quickly the first time
-Say thank you when I do something nice for you
-Talk in a nice tone of voice to me
-Talk calmly when you are upset
-be helpful
-do your chores without being reminded.
-put on your seat belt without being reminded
We bought a few hundred stickers...we go over the new requests on Sunday nights after we change them. Then everytime that he does something on the chart he get to go put a sticker on the paper. First week I think he got about 100 stickers because he really wanted to put the stickers on and "win".
In our house if he gets over X # of stickers per week - he gets to pick an activity to do on Saturday. So on Friday night we have the big count up and if the criteria is met he gets to pick what to do. We have ground rules...can't be more than 2 hours, can't be dangerous, can't cost more than $50. Some weeks he hits his target (we have been to chucky cheese, he had a play date with a friend, we went to an arcade) Besides chucky cheese these are things that I would have done with him anyway so it is not a big deal for the reward.
Key thing is that we hold to if you don't get enought stickers you don't get to pick what we do. When that happend the kid had to run errands with me on Saturday....terrible for me...but made a point for him. This has really turned around the behaviors to what we do want. Yeah!!!!
You could also say that they get to pick what game your family plays on Saturday, pick a prize from a grab bag, etc. The family that gave this idea to us has the rule that activity picked can't cost any money...so they usually pick going on a bike ride, playing in the snow, playing trouble or some other game with the family.
good luck