I am totally an impromptu shopper. I arm myself with my coupon box and debit card, and off to the grocery store I go. I do look at all of the grocery ads before I go to get a good idea of what is on sale where and what store will be the best for me to shop on any given weekend. There are lots of weeks when I shop more than one store. I always pull any coupons I know I'll use before I leave home.
Most grocery stores will have what are called "loss leaders". These are the items featured in the weekly ad at such a low price that shoppers just have to go to that store to buy that item. Call me crazy, but I stock up on those loss leaders and use coupons to bring the price of those items down even more. It requires a place to store those items, but the money you can save is tremendous! I never pay full price for things like ketchup, mustard, salad dressing, pickles, canned fruit and veggies, dessert mixes, biscuits, etc. I buy them when they are a featured item and use coupons from my coupon box. They are often free or close to free.
My weekly meal plan is devised as I cruise the aisles of the grocery store. I have a pretty good idea of what I have in my pantry/fridge/freezer at home, and I plan my weekly meals around the items that are on sale that week. Special produce pricing really influences my meal planning.
One of my favorite websites www.homemadesimple.com has an online shopping list. I plan to give it a try. Maybe, just maybe, I can become a list shopper. The list is organized to match the layout of most grocery stores. I don't know about you, but I tend to have to go back an aisle or two to pick up another ingredient that I didn't think I'd need until I decide on a menu item for the week. Maybe planning could be a good thing . . .