Cash, cash, cash!
In 2009 I made the personal switch from debit cards to cash whenever possible. I never carried any credit card debt, and I still don't. I have more discretionary money now than I *ever* had playing the debit card game. It was one of the smartest moves I ever made in my life.
As an added bonus, small businesses are often willing to give me a discount just for asking because they don't have to pay 3-6% in credit processing fees.
(Yes, much of the world's business is on-line transactions. I maintain a debit card exclusively for use on-line. When I make a purchase, I log in to my bank and transfer funds over.)
I cannot emphasize this enough: Nothing else changed in my financial picture when I switched to all-cash. However I have more money now to buy what I want than I ever did before.
For personal security, refer to the 2nd Amendment. However, while it would suck to lose the money in my wallet, my discretionary funds are up so much that it wouldn't hurt me. It is a truly liberating feeling to have this kind of personal financial freedom.