MAKE A LIST AND STICK TO IT
I mean walking into a grocery store without a list is a sure way to sabotage yourself from the start.
Take some time while you are in the parking lot before you get out of the car to go over your list. This will help give you a running start when you enter the store.
SHOP ALONE WHENEVER POSSIBLE, AND WHEN IT DOES NOT PLAY A GAME
If you have younger kids that you must bring with you, it can help to turn the whole shopping excursion into a fun game by getting your kids involved.
Make sure you have a pen to mark off your list as you go. It is SO much easier for me to visually see when I am almost done shopping.
Never shop hungry
Because no matter how great your plan, your list will inevitably get thrown out the window the moment you spot the first clearance rack filled with bakery goods.