Children screaming their lungs out in the grocery store, does it sounds familiar? You tell yourself that is not going to happen to my kids. But thinking and doing is not the same thing. There are some ways to minimize the drama though.
First step; make sure your child is not hungry or tired when you are going to the store.
Second step; never give or buy anything for your child in the store. If you sometimes buy something to your child but not always, the child will get confused about the rules. Always be consistent. It is hard and boring but pays of quickly and gives a very good relation with your children.
Third step; with older children you can give them some money before you go inside the store and tell them that they can buy for these coins, not more.
Fourth step; allowance. Let them save up for the things they like to buy. It will give them better understanding of that you cannot always afford everything and you sometimes have to choose.