If you are going for a regular shopping, always use a basket insted or a cart. Especially in big malls where they have a lot of items. It is easier to control yourself when you see items in a small basket than in a huge cart.
Bring your own bag to grocery store, so you won't need to spend any money on the plastic ones each time you go there. If you won't, use plastic bags any more you will do a great thing for our ecology as well.
Always check expiration dates and don't buy too much food with short storage duration so that nothing will go to garbage because of being spoiled and you will save some money by not buying anything needless.
Carpool with your coworker regularly and it will save a part of the sum of money you usually spend on gas. Also, you will have a good chance to get to know your coworker better while you are going at home, you don't have so much time and ability to talk about personal life at work.