Alright, I am an impulse grocery buyer. An impulse grocery buyer who ends up not being able to buy all the basics sometimes, because I blew the budget else where. Usually wandering the store, while hungry, not sure what we need.
So, I made a master list.
A list of all the basic necessities that we need to aim to keep in stock (milk) or like to have at least once a month (pot roast). On the first of the month, I compare the list to what we have in the house already. Mark off what we don't need or want and make sure the rest of the list is the first thing in the cart. Any food budget left can go on whims and cravings.
My list is broken down by department, of course, and then in order of how we come upon them in the store we shop at. The master list is 4 pages long. It's nice not to have to search around for what we need aisle to aisle as we enter them.
And when we stick to it, life becomes much easier around here. You don't want to see my boys when we run out of ketchup well before we can stock up on more!