Set the tone for your trip. Discuss what type of behavior you expect from your children before shopping, and praise them when they demonstrate good behavior.
Don't shop when you or the kids are hungry and/or tired. Taking a toddler to the store at naptime is only asking for trouble. And be sure to change your baby's diaper or have older children use the potty before you head out. Wet or uncomfortable kids aren't happy kids.
Shopping lists and time are of the essence! The middle of your shopping trip is not the time to decide what to make for dinner that week. Don't step into the grocery store without a list and a plan; if you're familiar with the store's layout, organize your list by aisles to avoid prolonging the trip by going back and forth within the store. If you shop with coupons, organize them ahead of time. Frequent stops lead to boredom and frustration for kids, so keep moving.