I only branded products on offer like certains cereals sauces and baked beans. They are on offer most months in at least one supermarket so i use mysupermarket.co.uk and stock up.
I buy clothes and products only when on sale or from ebay/amazon and i have a 50% rule. That it must be 50% off or more. I plan ahead so i rarely have to rush out and buy full price, in fact its been years since ive bought full price anything.
I know loads get charity bargains but im not that lucky and my local ones are over priced and ebay does better but shopping around allows me the luxury of bags shoes and accessories, i otherwise would not afford and quality items ie £150 bag bought new from ebay for £25 instead of buying a cheap non leather non quality one for the same price.
If you see an offer and know you will use it then stock up and if you see an offer and know you can sell it on then buy it. Tesco and argos toys are cheap in august sept and early oct, great for putting on ebay in nov and dec, they still get a bargain and you make some money.
I have never bought cinema snacks as my mum never did but we still had popcorn and sweets and drinks that we had chosen beforehand for a fraction if the price and always do packed lunch on day trips.
Use compare websites for all insurance and cashback sites, find online vouchers before making all purchases and wait if necesary, a week or a month without a washing machine isnt so bad if you save a few hundred. I went 9 months a few years ago without a second sofa as only wanted a quality one from ebay and it took that long to find it but i did. ( and it had to match my purpke velvet 2 seater which it did being the matching 3 seater)
Admittedly im cheap but you wouldnt know it to look at me (hopefully) still have nice things but love a bargain.