In addition to using coupons, I use the Walmart app when I shop there, and Ibotta and Checkout 51 apps for grocery shopping.
For Wal-Mart, which is pretty much already the cheapest store in town for most things, I use their savings catcher feature where you scan in your Wal-Mart receipts and they compare prices with local stores and if they find a cheaper price they will track the difference for you and you can cash it out for a Wal-Mart giftcard whenever you want. I'm at about $10 on a handful of receipts and never really expected to get much.
Ibotta gives you money back for featured items at almost all of the chain grocery stores and other chains that sell groceries. You can get anywhere from like a quarter for something like a loaf of bread to $2 for certain brands of beer, wine, or spirits. I like that for things like bread, milk, and eggs, the brand you buy doesn't matter so for something I was already going to buy, I get money back.
Checkout 51 doesn't care for the most part what store you go to but they only have limited items each week. But there are times where they give money back for something like onions, bananas, etc. I'll buy the smallest quantity or the smallest weight of something and sometimes get more money back than I even spent!
Ibotta will let you cash out via Paypal when you reach $20 and Checkout 51 will let you request a check when you reach $20. These savings in addition to coupons add up pretty quickly.