Congrats on getting married next year.
Some ideas for you.
1. Buy large boxes of Cereal, but buy large biscuit ones, not little biscuit or flake ones. Little Biscuit and Flake types can be harder to monitor for usage, but big biscuit style ones are easier to monitor, so you use only what you need, never more than you thought.
2. Two for ones and three for twos are good, and so are % discounts too.
3. Buying larger in general works out better, so things like 2 pint Milk cartons instead of 1 pint for example. The probable reason for this is, that something with 2x the content, isn't 2x the size, so you use less packaging and people hours and it's better environmentally as well, as this is the age of recycling, being green and Carbon footprints and all

4. Bulk buying Meat and Poultry is another example. As often they do come in bulk buy bags, as well as individual quantities.
5. Also be a bit sneaky and try haggling. If you're in small shops buying stuff, it might work. Obviously if you're in a big supermarket, you can't really haggle with somebody at an Epos, but a shop owner standing behing a counter, might be willing to give you a bit off, if you haggle for it, like maybe 2%, but even if you bought say $100 of stuff perhaps, that's still $2, so that's something, even at that low haggle percentage.
Or maybe haggle for items that might possibly have a little problem, like a slightly damaged packet or something like that. Just don't damage them on purpose, because if you're seen on a security camera, you could get barred.
You might find some small shops have a discount food bin perhaps, for stuff hours from the sell buy date, or a bit damaged, but still usaeable.
Plus some small shops might value you more and agree ot haggling type buying, if they are those who like the personal touch. Big places generally don't too much.
6. Possibly use loyalty cards, not credit Cards though, as they give you too much freedom to overspend possibly by mistake, or use schemes where you bring back stuff like Egg Cartons or old bottles, and get given a small return on them, like 5 cents for example.
7. Don't buy from the same place for everything. If you can go to somewhere else nearby, even to get just 10% of the items you want, because they're cheaper there, that's better because the extra walking won't be that bad, and you'll save a bit of money.