I am sure you use plenty of common sense just keeping it down to $1000! Some things I have learned to do-never pay more than $2 (or so, I will go up to $2.16) for a lb of cereal. The kind you like will be on sale, stock up then. Stock up on coffee, TP, deli meat(freeze in smaller or sandwich size portions) Laundry soap can be super $ or super cheap-depending on sales. Stock up when cheap. Cheap cuts of meat-chuck roasts and all will cook slowly all day and taste SO good and tender at night. Buy chicken breast in bulk when $1.99 or so a lb. Whole chickens can be very inexpensive. I clean and rinse them right after buying them and cook or freeze immediately. If they are clean and ready to go, it is SO easy to roast quickly and not be tempted to spend too much on 'easy/quick' food. Check out who has the best deal on milk. It can be worth it to go to more than one store (best limit it to 2 or you use all your time shopping). Spaghetti sauce is often had for .79-99 cents for a big can. i put a few frozen meatballs in it (ok, I nuke them quick first) for the meaty people in our family, the rest of us have it w/o and it is a cheap meal.
Some things go on sale cyclically-take advantage of them, be aware of the good deals.
Know what a good deal is! Don't be fooled by endcaps.Sometimes they are great deals, sometimes they have a great deal mixed in w/no deal at all and it fools us! Careful.
If you have time, the least processed food is best for the family and the budget. Wash your own veggies, cut up your own chickens. Learn good substitutes. Try to only go to the store one time a week. If you need milk/bread later in the week (things I can't freeze for my crowd) send in a kid with explicit directions and the right amount of money. I have found this keeps ME from going in there and buying things I don't need/want/afford. That way my midweek 'pop into the grocery store' doesn't turn into a YUM, that looks good feast to the eyes.
OH, most importantly, plan menus and shop with a list.
And if hubby likes to cook, involve him in it, and have him cook enough for everyone on some nights and save and reheat for the next day. Save you from the cooking, plus, if everyone is eating the same thing, it will save money, unless he is eating filet mignon.