Pay With Cash Rather than Credit Cards
I've got to disagree with this one. Obviously if you're spending money you don't have, then credit cards are a disaster waiting to happen, But if you're on top of your finances, credit cards are so much better. Cash back, rewards points, and bonus programs are the tip of the iceberg.
You also get to dispute claims through the company, identity theft protection, and a permanent record of your spending habits. If you lose a wallet with $1000 in cash, it's as good as gone. If you lose a wallet with ten credit cards in it, it's a pain to deal with but your money is probably fine.