Sometimes we buy things because we need them, but just as often, we get excited about spending money because purchasing something new and exciting is fun in and of itself. That's the danger of the impulse purchase: Once the excitement wears off, there might not be a substantial need or lasting want behind it. And that's a surefire way to waste money. To prevent that kind of waste, set up guidelines to restrain yourself before making new purchases. The more expensive and frivolous, the more important it is to make rules to keep yourself from impulse spending.
Try this: Live with a one-month waiting period for any purchases that deal with entertainment or fun. If you don't need it, hold off for at least four weeks before buying. This is the testing period to see if you really want the object of your affection. After that month is up, you may find the allure has vanished. You don't really want it anymore. Money saved!
Simply budgeting in those purchases helps, too. If you set aside $50 per month to spend on movies or video games or books, you'll think harder about where you choose to spend that money. Sometimes you may decide you don't need to buy things at all: You can make them yourself instead!