I think the key is to know what you want to spend, double check you can actually spend that, then be sure you actually want what you are spending on.
Also, it is occassionally okay to indulge on an item and use your credit, but be sure to pay it off before going to the next purchase. For example, I bought a TV in 2007 when flat screens were still $2,000 and I didn't have $2,000. However, I made sure I paid off that TV over the next 12 months before making another purchase. There is a financing cost associated (thankfully only a few percent for that purchase), but you can weigh cost-benefit ratio of instant gratification + interest versus waiting and paying no interest but not having an item for 12 months.
What gets dangerous is if you get that $2,000 TV or $300 game... but then you buy another big ticket item before paying off the first. Then maybe you buy two or three more items. You can find yourself in a hole you cannot possibly climb out of really quickly this way.