Gather the ad of your favorite local grocery store. What's on sale this week? Is it anything use regularly use? Yes? Then buy as many as your budget will allow for the week. For example, let's say that butter is on sale for $1. That is cheap and can freeze so buy 10. If you do that every time one of your staples is on sale, you will eventually reach a point when you will be able to wait to buy that item until it is on sale again. Another example is we buy tubs of Electrosol dishwasher detergent from Costco (I tried making my own for awhile and hated it). We know that if we buy two tubs when they are on sale they will last long enough to get us to the next time it's on sale.
Another thing to look for at the grocery store is the in season fruits and vegetables which will always be cheaper. Not sure of what is in season? Let Google help you.
The lesson? Pay attention to the ads. I am not a coupon clipper because the coupons that come with the Sunday paper are all for products I don't buy. I don't clean with chemicals and I don't regularly buy processed foods. If you buy that stuff and pay attention to what is on sale, I am certain you will save even more money at the grocery store. As it is, we usually spend around $100 every two weeks for a family of five.