Grow what you can - especially things which grow easily and can be added to tons of meals (like zucchini and potatoes) and things which are pricey (like scrummy fresh herbs)

Look more broadly than just food when trying to reduce your shopping budget (are there less expensive choices when it comes to cleaning products / cosmetics / paper products / etc?)

Cut out softdrink, limit alcohol, juice, etc

Buy meat in bulk - we know someone who has a family member farmer - so we buy a 1/4 cow every few months, meaning that the meat is a flat $7 a kilo for everything from pure mince and chuck steaks to prime rib and porterhouse ... other meats we get at Costco - really cheap. We buy it, bag it into serving sides and freeze.

Like Div, we cook up big batches and freeze - limits your cooking costs, and means you're not overeating - you've already portioned it out.

Think about what you're buying brand name but generic would be just as (or almost as) good. Some things are identical products just in different boxes ... and some stuff, you're really not going to notice the difference much. Tinned beans, rice, oats, sultanas, etc. Other things you might notice the difference, but you can manage (tinned tomatos, gherkins, coconut milk, tomato paste, etc) and others you might get some generic (for cooking) and brand name for other - eg: butter. Butter on bread - you want a nice one. Butter in cooking - might not matter.

Stick a sheet of paper on your fridge and every time you have to throw something out because it's gone off, write it on the fridge (and make sure the rest of the family does too!!) - you might be surprised how much gets piffed over a month. Alter your shopping habits to minimise (dare I say eliminate?) wastage. Or if something is getting close, make soup / lasagne / pies / curry / something you can put them all in, to avoid their final demise.

Invest in really good crispers - the Tupperware puppies keep veggies fresh for a scary amount of time.

That's all I can think of right now ...