Yesterday, I went shopping and got free Lipton Green Tea (1.5 liter bottle) using a coupon printed at checkout on a prior trip. I had $5 in "$X off your next order" that was printed on a prior trip. It paid for the kitchen bags that I needed to buy (which, incidentally, had a 55¢ off coupon attached to the box). I always check the coupons that print out at the checkout to see if I can get anything for free or almost free on a future visit.
I got a free bag of Purina One dog food using a coupon that I got by calling their 1-800 number and requesting it. I'd have to say that I get the best coupons from contacting the manufacturers. Anytime that I've had a problem with a product, customer service reps almost always send me free coupons so that I'll continue to use them.
I also got a 10 oz. bottle of Teryaki sauce for 79¢ because it was on sale and I had a 35¢ off coupon that got doubled. I try to match sale items that I use with coupons that I've clipped. It's not uncommon for an item to go on sale within a week or two of the coupon appearing in my Sunday paper. The grocery stores in this area are very competitve and almost all of them offer double coupons all of the time.
And, I am not above "buying" coupons if there are some good ones out there for items I purchase often. There are actually websites out there that will send you coupons for a fee. The cost is less than the face value of the coupon, and with doubling it still saves me a nice bit of cash.