Shop around. I do my weekly shop in Iceland, Farmfoods and Aldi. Shopping around can save alot of money. Buy in bulk and stores own brands where possible.
Petrol is a biggy. Walk to your local shops rather than driving and avoid pointless trips through the week. If you can.
When you leave a room, turn everything of at the mains eg dont leave the telly on when you go for a shower etc
Dont leave heating on over night. Only have it on when you are at home. Wear a jumper if it is a bit chilly rather than turn the heating on.