If you really want to get the most bang for your buck you'll want to learn about these two techniques.
Stacking is using a manufacturer's coupon and a store coupon at the same time. The majority of stores will allow you to do this but double check your stores coupon policy to make sure.
Of course you're going to need to know the difference between manufacturer's coupons and store coupons.
The insert coupons in the Sunday paper are almost all manufacturer's coupons. When you contact a company and they mail coupons they'll be manufacturer's coupons. Often the booklets, blinkies and tear pads in stores are manufacturer's coupons but sometime they're store coupons so be sure to double check. Most coupons are manufacturer's coupons. Manufacturer's coupons will always say "Manufacturer's Coupon" or "mfr coupon" usually it's near the top by the expiration date but it an be anywhere on the coupon.
Store coupons can come in the mail from the store, be printed from their website, or picked up in the store. They sometimes show up in the Sunday paper inserts too. A store coupon will say "Store Coupon" or it may name the store "Target Coupon" for example. A lot of the time these will also have the store's logo printed on the coupon, but don't assume it's a store coupon just because there is a logo. Sometimes manufacturer's will limit the use of their coupons to certain stores so read the fine print.
So if you have a manufacturer's coupon for 50 cents off toothpaste and a store coupon for 50 cents off the same toothpaste you can use both and save $1.00.
Piggybacking is another way to use more than one coupon and it's my favorite way to coupon. Piggybacking requires some strategy and strategy is my favorite couponing tool!
Let's say you have a coupon for John's BBQ sauce and you have a coupon that says "$1.00 off your meat purchase when you buy John's BBQ sauce" you can use both and save on the John's BBQ sauce and the meat.
Sometimes these coupons confuse the register/cashier and be sure you're buying the required items and be prepared to explain the deal if the cashier has a question about it.