Cash Only Spending

One sure way to save is to only use cash when you shop. If you don't have your credit or debit cards with you and you run out of cash you can't spend anymore. 

Some use the Envelope System from the Dave Ramsey books. But I think that whole system is just another excuse to buy something else. 

Just use normal envelopes. Label for Food spending, Household needs, Gas, are a few of the options. Use what your family uses as labels. Some might want cash for movies and entertainment. Other families won't. Put the cash you budgeted for that category for the month and put it into the envelope. When you shop, use that cash and when it is gone, you don't spend on that category anymore for the month. 

It may feel embarrassing to have to return things at the checkout if you run out of money for it but that small bit of embarrassment is small compared to the amount of money you would save with the Envelope System.