I make my own cards - you can afford to buy some pretty essentials from craft-shops and STILL save a fortune on buying the things. I use a lot of recycled materials too - other cards, ribbon, sweet wrappers, foil, wrapping paper, feathers, string, pressed flowers and herbs.....
Making jams and chutneys (chutneys are easier!) - it all looked very difficult until I tried it; but they make great gifts, especially when packaged with some homemade biscuits. The computer means you can make lovely individual labels cheaply, without buying labels.
Meal planning - I have barely thrown a scrap into the composter. Which may be why I'm not making much compost! When you peel potatoes, if you do with a knife rather than a peeler, you'll get thick-ish peelings that you can cook in the oven, coated in a little oil and herbs, which make a lovely accompaniment to dips (if you have the wherewithall to put the oven on!! Mine only goes on once a week, but I cook loads at the same time). Put an apple in with your spuds in the cupboard to stop them sprouting.....when you make vegetable soup, whatever is left over can be added to hot oil and spices to make a lovely veggie curry the next day.
Freeconomy - Google it! I'm making two cards in exchange for a nice man coming and cutting my berberis hedge for me (and taking the trimmings away) ; and I'm ironing 4 blouses in exchange for 6 freerange eggs.
Turn all your heating off, and wear jumpers / use blankets. Never use the cooker on the same day as you use the washing machine (you can watch the meter happily spin round!) - nightmare for me with two messy kids, one of whom wears reusable nappies, LOL! Casseroles can be cooked on the hob, with a decent pan with a fitted lid, even if the packet says cook in the oven. Similarly, ovenchips can be cooked under the grill, as long as you are prepared to watch them.
If you are on a prepayment scheme for your energy - do you own meter reading via your energy company's website - the energy companies are b%stards and base far too much on estimates - our 'estimate' was £124.00 a month (they average your usage over the year in 'convenient' monthly payments of the same amount - it's only convenient for them, really!) - actual usage was £63.00 a month in the depths of winter - £29.00 per month in Spring/Summer/Most of Autumn (electric only- we don't have gas, white meter heating only on in one room, but supplemental use of timer-set oil radiator heated from mains to warm up boys' room, and occassional blast of three bar fire; but washing machine is on most days because of nappies - I do clothes/sheets/towels one day, then nappies next day, then hopefully a break day to catch up with the ironing, then more nappies) - yes, you DO get your money back at the end of the year, but why the hell should that money be earning THEM interest when it could be earning you interest?
If you buy mushrooms, tomatoes, punnets of fruit, margerine or yoghurts from the supermarket; you will never need to buy another pot for growing seedlings. Beans and sweetpeas can be grown in the inside of toilet-roll inners, squashed into one of the blue tubs you get mushrooms in. Newpapers are great for laying down as mulch for a no-dig border - just lay it down as you would plastic you would normally buy.
Freecycle for clothing. Great for children's clothes. For adult clothes, if they are not to your taste you can always turn them into something else - peg holders / nappy stackers for carboot sales, quilts, cushion covers.........
My God, have I rambled enough???