My fiance is the King of Coupons, and his diligence in using coupons and on buying on sale items is amazing. We regularly save 33% or more at the grocery store, and we never buy something we don't really want just because it's on sale.
We also save a lot by belonging to the local food coop and buying at a wonderful local produce market where prices are always significantly lower than at the big box markets.
As for me, I am the Queen of eBay! It is my first stop when buying almost anything, certainly clothing, shoes and household items. I am also a big fan of buying used (or, as I prefer to say, "pre-loved" :-) items at antique or second-hand shops.
Another tip is to explore the store brands, especially on beauty products. I use a wonderful moisturizer that would be a very costly product, but I buy the CVS version; it is usually 25% less, more when on sale.
Other thoughts: Check with your vet to see if they offer a discount if you bring multiple pets in for their annual exams at the same time; most do. If you haven't joined a club store (Sam's Club, Costco, BJs) then do so--your savings can be remarkable and they have responded to requests and have smaller-sized packages in stock now.
But the biggest savings of all come from Do It Yourself. Teach yourself how to use basic tools and tackle small projects first. The money you will save can be absolutely astonishing, plus you will have the satisfaction of knowing the job was done right--and the priceless ability to say, I did it myself!"