Searching the web for coupon/discount codes - I have a few extensions enabled to do the searching for me, but they haven't been working as well of late. So, I've been hunting manually. I saved $32 the other day on the dog's flea/tick/heartworm refill. It's not even just meds. The last time the kids wanted pizza with their friends, those extensions found some Papa Johns discount codes that saved me about $45.
Good RX - DD18 has severe food allergies and requires life saving meds on hand at all times. The cost of these meds (even with my insurance) is astronomical. I did a happy dance when generics were introduced, just to have my insurance company deny generic coverage. Some years (like this year) her doctor has been able to procure a good coupon that will work for us, but many years, I have had to rely on Good RX. It's still not cheap, but it's about 75% cheaper than buying name brand through my insurance.
Thrifting, Garage Sales, Season End Sales, Outlets and Bargain Stores - This all sort of mortified me when I was growing up. I loved the spoils of a good bargain hunting adventure, but the kids at school questioned every bit of it. The snobbery with the girls where I grew up was just so out of hand. Still, it was big with my mom and I not only learned that you could find some amazing things, it was a good budget saver. In fact, I still own and use some of her better finds. Thankfully, all of this seems to be really popular with a lot of kids these days...so, no more shame in finding low priced treasures.
Honorable mentions...Jumping on discounts for Disney lodging/packages when they come out, ValPak coupons for some of our favorite local restaurants, DHs Buc-ee's card that saves us both inside and at the pump, scholarships of all sorts, cooking for ourselves vs. going out to eat all of the time, Kroger fuel points to save at the pump, Costco gas (because paying $3.80/gallon during a CA visit was a real score), Costco gift card deals (I know the Disney one is popular but we've been using it for Southwest),
Undercover Tourist for tickets, cashback rewards/perks on credit and debit cards, store brands, and the discount bakery and meat sections in Kroger.