Take away his favorite toy , this works for dd1 (4), she gets 3 warnings, 1)i threaten to take it away if she doesn't do as she's told. 2) i get a bin bag out to put the toy in, 3) toy goes in bag and out of reach.
Last week i took her playmobil ship away, she had to be good for the rest of the day to get it back, she was a little angel.
We also use the 'im going to count to 3 and if you dont do as your told you will have no chocolate for the rest of the week'