Red Plum and Smart Source are available on line but also in the Sunday paper. One of the programs I've seen recommended on TV is The Grocery Game. You can usually try it for 30 days for free, then it's something like $5 a month. I didn't get a lot out of it because I don't buy most of the products they covered -- but I don't have little kids and I also don't always buy name brand or processed foods. You can get coupons sent to you through them, and you just click on the ones you want, and then print only those. I have a friend who saves a fortune doing this. Combine them with stores that do double coupons, of course, and watch the market circulars - sometimes they have bonus coupons that will double a $1 coupon (which doesn't double under normal circumstances). Get a coupon file and organize it by category or by supermarket aisle. I have 2 - one for the regular market and one for BJs (they send their own coupons). Usually you can take a regular manufacturer's coupon for 2 packages of something, and combine it with a BJs coupon, and the mfr coupon will scan for a single BJs item if it's a multipack. If not, the clerk should scan it for you. Doubling up is where you really see the savings.
I keep a couple of big paper clips on the front of the coupon file - I pull out the coupons I plan to use and put them there ahead of time (in grocery aisle order), or reach into the file when I'm in the store and see a deal - then when I get to the checkout, the coupons are clipped together and ready to be scanned.
Also keep an eye on rebate deals, and save the receipts or bar codes, whatever they want. It's worth a stamp to get a check for $3 or $5.
I clip coupons while watching tv, stack them in categories, then file. As I file, I pull out anything that is about to expire, and stick it in the paper clips so I'm sure to buy that item. I also put a dot next to items on my grocery list for which I have a coupon, to help me remember.
Coupons only work when you are really flexible on what brands you buy. Also, sometimes a $1 coupon off 2 packs of a name brand is still more expensive than the generic or store brand - so be careful while you are first getting started. Also, saving $1 on 3 gallons of ketchup you will not use up in a year is no bargain.
And be careful using coupons for packages of 100-calorie snacks. The snacks are already way overpriced compared to just buying the basic product and using your own snack containers or bags (especially reusable ones). So coupons aren't worth anything on those items because you're already paying so much more.
Some people on TV have these elaborate notebooks where they 3-hole-punch the circulars and flip through the pages. I can't imagine spending that kind of time but I suppose if you have a lot of kids, it makes a little more sense.
The other thing these people on TV do is recognize when the sales start - usually Thursdays. If you plan your menus around the sales, and then add in the coupons, it makes a difference.
