I give my boys a treat at the shops when they are being good. If they play up I tell them that thay will go to the car and go home with no ice cream, lolly or whatever they ask for. I have to follow up my words on occasion and just walking to the carpark snaps Mason into line.
I've tried the sticker thing and I think mine are too young to understand how it works. Mason throws a wobbler when I put the stickers back in the cupboard, he wants to stick the whole sheet on the chart #-o