First of all, ensure that you have a frugal store cupboard. There are certain items which every cupboard needs (Essential Store Cupboard items):-
Within the recipes these items are 'a given' and are not factored in where 'per head' values are given.
Secondly, ensure that you always make a frugal shopping list. Don't pick up anything (well, not too much!) which isn't on your list. Check carefully what you already have in your cupboards before shopping. It is pointless buying food that you won't use in the next seven days - you are going to end up throwing it away, you may as well just chuck your money in the bin.
Thirdly, Take advantage of the buy one get one free offers, but only if you will use it, or freeze it.
Fourthly, and most importantly, MAKE A MENU PLAN!
A frugal menu is the crux of everything frugal. It sounds like a pain, and sometimes it is, but if you plan your meals in advance you keep control of your spending.
Put the menu on the kitchen board so everyone knows what they are getting.
By planning your meals, if you are having to buy, say cream, make sure you have the right recipes planned to use all of it before it goes out of date.
Try one of Faye's menu plans - by signing up above
Finally, try growing your own goods and herbs - its not as complicated as you may think. Seeds grow if you put them in compost on a sunny windowsill. Tomatoes transplanted in to a grow bag and supported and watered regularly will provide you with tomatoes at a fraction of the cost of buying them. You can buy established Tomato plants from individuals who have grown too many from as little as 50p each, you will recoup this with the first three tomatoes you harvest. Try buying peppers and cucumbers the same way if you have a sunny patio. Remember that you know people who garden - ask your friends and family, they will probably be happy to give you a chunk of their Sage, Parsley, Mint or Thyme and "hey presto" instant herb garden.
Who knows where it will end, its very satisfying. Try it.