Make your next trip to the grocery store as healthy as possible by shopping the perimeter of the store:
That's where all the fresh foods are. The less you find yourself in the central aisles of the grocery store, the healthier your shopping trip will be. Make it a habit—work the perimeter of the store for the bulk of your groceries, then dip into the aisles for staples that you know you need.
For the most part this does actually work; it makes it easier to avoid the sugary/fried stuff and stick to a healthy shopping list.