When you're actually at the store keep your eyes open.You may find peelies, blinkies, tearpads, winetags, booklets, and catalinas.
Peelies are those coupons that are stuck to a product. They usually say something like "Save Now". If you don't peel them off yourself, make sure the cashier notices and peels them. Sometimes it better to save them for use another day, especially if you already have a good coupon/sale deal on that product and the cents off on the peelie is less than your coupon.
Blinkies are the coupons in those little machines that stick out from the shelves. Usually you pull a coupon free and another pops into it's place. They're called blinkies because those machines often blink occasionally they even make a noise or sing a jingle as you walk by.
Tearpads are just what they sound like. Pads of coupons usually stuck to a cardboard display that you peel away. If it's a good deal, don't be afraid to take a couple.
Wine tags are not available everywhere but they are coupons that hang from the necks of wine bottles. Usually they're coupons for meat to go along with your wine. They may also take the form of a cardboard wine carrier with deals like "Buy 4 bottles of wine and get $10.00 off your order"
Also keep your eyes open for idea and recipe booklets. These are often free and almost always include coupons.
Catalinas are those coupons that print when you check out. They're called catalinas because that's the company that makes the printers. They're usually aimed specifically toward you based on something you just bought. Some can be used buy anyone so feel free to trade them, others are tied to your shopper card and can only be used along with it. Some catalina's have an area to write you name and address, do this and you may receive coupons in the mail. Usually catalinas are store coupons and have to be used at the store you relieved them.
Sometimes there are even coupons loose on the shelves. These are placed there buy the store to encourage you to buy a product, by reps coming in to replenish stock and even generously left there by other customers.
Store coupons come in the form of catalinas, are printed from the store's website, come to you in the mail, or are sometimes tucked into a sales paper. They vary from manufacturer's coupons in that they can only be used at the store they're connected to (unless you're lucky enough to have a local store that honors competitors coupons). A plus with store coupons is that sometimes they can be stacked with manufacturer's coupons. This means if you have a coupon from the Sunday paper for 25 cents off Coke products and your grocery store mailed a coupon for 50 cents off Coke products, you can use both and get 75 cents off.
Rain checks aren't really coupons but I'm going to include them here anyway. If you visit your store planning to take advantage of a sale only to find they're sold out of that product you can visit customer service and request a rain check. The rain check can be used at a later date when the item is back in stock to allow you to get the sale price even though the item is now full price again. Rain check expiration dates vary from store to store, some are honored forever, some only for a month. Some stores don't issue rain checks at all and some stores restrict them during especially good sales. You'll have to check your favorite store's policies to find out how they handle it.