I follow a few of the coupon people from the show Extreme Couponing -- now, that being said, the show put on a lot and fabricated or stretched couponing truths, but the people on the show do coupon and run their websites and social media pages with deals for you to check out. I also follow the krazy Koupon lady but there is a lot of ads on the site. One that I really like is Hip2Save. I don't spend much time going into it or looking through it. I sign up for sites or follow their pages so I can see what is "hot". Often times, the really good deals are kept a secret for a while until everyone has racked up hahaha. I spend a few minutes just browsing the list of coupons on a few sites I know are safe. I make a habit of NOT BUYING JUST BECAUSE IT IS CHEAP. That's how you end up with 18 bottles of ketchup and 26 bottles of mustard you cannot use and other people just take "because". I did stock up on laundry detergent when they came out with a $3 off coupon for my brand and it was on sale for $2.99 at a local store... I bought like 60 jugs... and everytime I walk by I shake my head at myself.
I do a few of the apps for cash back too. Ibotta is a great one, and so is Checkout51. There are also receipt pal and receipt hog. Just don't get too caught up or you'll waste a lot of time. For the receipts, I scan them right after checkout to be done with it. I make $1 a week doing that but when you cash in at Christmas, it can be nice. Ibotta rebates can be hefty sometimes and often combine with coupons. Toss in your mystery shop and you may come out like a bandit. Example: Crest Glamorous White toothpaste had a $2 back and was on sale for $2.99. I also had a coupon for $1 off. I got it for a few cents tax but it was a mystery shop that I was already getting the product for free anyway. These are far and few between sometimes.
Occasionally money maker coupons come out. Walmart will give you cash back if you go to the ones that are friendly and do what they're supposed to. Many are getting in a bunch about coupons simply because they don't want to deal. I usually hit the self check out machine, but if your coupon is worth more than the product, it will set off a "call CSM" alert and then the manager comes and that can be a headache too.
Just like mystery shopping, find a balance, spend a few minutes checking out the deals, and don't stress too much about huge savings. Sure, you can save 25-50%, but the shows fool you into thinking you'll save 98-99% EVERY TIME. Those extreme coupon people make money from their websites and blogs and ads, so they can spend 40-60 hours a week doing coupons.