Things that work for me are, doing cupboard/ fridge challenges for a week every month or so, this is where I don't buy any thing unless urgent and simply use only the thing in the house, it is quite challenging but fun as you get creative. This has lead to some family favorites being created.
I am lucky enough to live on 6 acres so I am able to grow alot of our staple foods like potatoes, pumpkins, peas, carrots, the list goes on so this cuts down heaps on the fuel costs and fruit and veg. costs. As Bath said taking the time to collect seeds keeps costs down to a minimum.
I am also fortunate to have great family, friends and neigbours who all share there excess foods amunst each other, for example my SIL keeps chooks and I get my eggs from her, I harvested quite a few kg of spuds recently and shared some with her, this happens all year round and I find that we eat mostly thing that are in season. I know not everyone can do this but it may trigger you to think about other ways of "shopping." Along the same lines, friends of mine in Brissy go shopping at the bulk outlets and save by dividing up the tins, loo paper etc amongst themselves. This seems a bit more involved but works for them.
I also clean using vinegar bi- carb, tea tree oil eucalyptus oil and lavender oil I mostly only buy powder for the dishwasher and liquid for the clothes, I have some bottles of cleaning chemicals still in the cupboards that I bought from my old place 3 years ago.
I look forward to following this thread to see what other great ideas are out there.

