For me personally it’s quite simple - just don’t spend!! I’m terrible for frittering away my disposable income (always have what feels like a million things on my wish list) so I’m trying to fix that now by only making considered purchases that I actually need or really, really want. It’s a work in progress but I’ve made some improvement and it’ll get easier as I make it a habit.
So for example I have wanted a coordinated picnic set-up for a couple of years now and that’s what I’m getting this month as an early birthday present (because April/May tends to have the best weather and we want to go out a lot while it’s nice). Next month I might try not to buy anything at all, but if I see a brilliant bargain in terms of cost/quality I might get another summer jacket because that’s something I do actually need. I also need a flat-ish pair of dressy shoes for summer as I’ve decided not to wear heels anymore. I’d love a new pair of trainers in lighter colours to wear in the summer but I might decide against those and just make do with the olive green ones I have, even though they’re not all that comfortable - buying a pair of gel insoles will fix that for a lot less money!
I buy a lot of my clothes pre-loved now. I maintain a small capsule wardrobe and don’t buy clothing/accessories for special occasions anymore unless I actually have an event to attend. DH no longer buys any branded clothing (not just a cost-based decision, he loathes the preaching, moralising and lecturing they think they can do whilst taking our money and won’t pay them a single penny any longer).
In terms of household spends we no longer have a tumble dryer. We will be getting a pressure cooker soon and a slow cooker as well. I might invest in an air fryer combination oven if I can determine that it will save us money on electricity - we mostly cook just for the two of us. If anyone knows definitively that it is substantially cost effective (based on actual usage at home compared to a standard electric fan oven) then please do let me know! TIA 
We hardly ever have takeaways (mostly because the standard is abysmal in our town), maybe once or twice a year. That saves a lot of money. We also don’t routinely get substandard coffee/tea/cakes in coffee shops. I haven’t been to one in a couple of years now because of lockdown and I likely won’t this year until my daughters visit. We eat out maybe quarterly, if that. Probably more like 2, maybe 3 times a year.
We do one big grocery shop per month. Buy meat/eggs once a month from farm shop. We have veg delivered weekly. We bake our own bread for the most part. I only pop in to supermarket a couple of times a month to top up on sliced bread for toast (which is frozen as we only use a slice here and there) as well as things like milk & fresh herbs or specific veg. That way we spend less by not picking up lots of extra bits several times a week.
I don’t throw away any food. Every scrap is used, leftovers are used over a few days or frozen and made into meals later on. If I get a bit distracted for a week or two and end up with some veg or lettuce that’s past its best it all gets thrown into a soup and it’s always delicious. Very comforting and a quick and easy lunch/dinner.
We’ve switched off our TV and various boxes in the sitting room, because we hardly ever use them and they don’t need to be on standby. Same for PC/printer.
We’ve got a monthly budget that we save into a pot for nieces/nephews’ birthdays (there are a lot of them!) and we stick to it - It’s enough for a good present or a nice sum for a child’s saving pot if they’re saving for something they want, but we don’t go overboard.