Buy pricier household items in bulk.
I use a skin cream that costs £6, I usually always get it for £3 because I watch three places like a hawk. For about six months there were no offers to be had so when they came back I ordered 24. Same with deodorant, shampoo that is usually £7 a bottle etc.
Tin foil has gone through the roof. Do you have a booker or a macro? A few years back I basically made up a business and registered, they have never asked for proof. Our local Booker is the only place we are guaranteed crystal fresh veg and they sell some of it in vast boxes. Massive bags of mixed salads. Anyway their catering foil is something like £15-20 a box but it's big and long and doesn't tear like supermarket tat so is cost effective.
One thing the other half and I do is discuss any orders over twenty quid. Do we really need that new electronic thing that's £30 or have we been doing fine without it? We were hemmoraging money on Amazon because it's so convenient. Now we have discussions, we order a lot less.
Cleaners, I just ordered X2 five litre bottles of Ecover lemongrass, 25ml goes in a half litre bucket. I have diluted it and put it in old spray bottles for general purpose stuff like sinks, sideboards, stuff not too sticky or messy. Very cost effective.
Obviously look at any 2 for 1 deals in minute detail because supermarkets go out of their way to make you feel you are getting a bargain but actually aren't.
This is a bit extreme but I also transfer 2/3rds of our spending money for the month straight into our savings account on payday. Not only does it earn me more interest than I would otherwise get, but when I start transferring chunks over as the month progresses, we again have a discussion about it. I reckon by having to take a conscious decision to spend more money, we are probably spending a good 30-40 % less, purely because it is deeply satisfying seeing those savings grow so quickly.