Watching Your Wallet
Credit cards have been shown to make us spend more. Ryan Sager argues that this isn't the full story:
Every person’s financial situation and mind works differently. For some people, doing many more of their transactions in cash (or check you have to have some way to pay bills) would be a huge improvement. If you shop a lot recreationally, for instance, this could slow you down. For some people, just using a debit card could be the answer. For me and other people who like a lot of control and data and feedback...a solution like credit cards plus something like… Mint.com is a good answer.
The key, as in so many things, is a high degree of self knowledge, a willingness to experiment and track results, and the information to understand what biases might be driving your behavior.