2) Buy in bulk- when your only feeding yourself, or like me, only feeding two, sometimes buying in bulk amounts (particularly fresh items) can be a bit more difficult. However, when it comes to dry items, such as rice and pasta, buy in as large amounts as you can. Most shops sell 1kg bags of pasta/rice/cous cous, and most sell 2kg bags of potatoes. If you have one near you, Asian shops are very good for this sort of thing- you can get 10kg sacks of rice for almost nothing! Again, with most items, if you look at the per kg price of items, you will notice that products in larger amounts tend to be cheaper. If you happen to be lucky enough to be a member of a catering wholesaler (such as Bookers Wholesale), you can get some seriously good bulk catering purchases- sometimes you may find you have a mate who does event work/catering work that has a members card, that might let you borrow it for a little bulk shop.
4) Check out prices of your local fruit/veg stall/greengrocers/butchers- Make a note of the cost of a few things in your usual supermarket, and then checkout any local business around you and see if they may be lower. I know for a fact that a fruit and veg stall near me has much cheaper prices than in my supermarket. The butchers near me is fairly cheap, but it depends which cuts you are buying. The bakers on my street does deliciously amazing bread, but at a hefty price.
5) Buy tinned items, frozen veg, and dried pulses- There are certain things that are always in my cupboard/freezer, because they are such good value and they are good for use in loads of different recipes. Tinned tomatoes are a must, as they can be used in anything- from a pasta sauce, to a curry, to a soup. Frozen veg, of all varieties, are cheap and good value. Personally I always have frozen peas in my freezer. It's good also to have mixed frozen veg (a mix of carrots, green beans, sweetcorn and cauliflower normally) because that can be made into a quick healthy dinner really easily- without loads of prepwork. Dried pulses, if you have time for preparation, are one of the cheapest filling nutritional things you can buy. Ok so they take an hour boiling, or overnight soaking, but in the end it's totally worth it- often you can make at least 4 meals from a pack of dried pulses for less than £1 for a packet. And all of these, of course, have a massive shelf life.