Use a Credit Card (WOrld)

Credit cards offer a great level of protection against fraud, and they can provide you with amazing benefits like extended warranties and cash back.

They were designed to make you spend more, so if you are susceptible to spending more than you can afford you should stick to using cash or some alternate method, maybe a pre-paid credit card.

Many people prefer debit cards over credit cards but this is not a great idea from a security point of view and you miss out on many of the other benefits.  One of the world's best scam artists turned FBI agent won't let his kids use debit cards - video link

You might already have a credit card with rewards, but unless you took 10 minutes to seek out the best reward program for your situation you can probably double the rewards by switching.

The benchmark for a good rewards card is 1.5% cash back on every purchase. In Canada the Rogers World Elite Mastercard has this.

You can click this link to get to a spreadsheet I made which will compare all the best cards out there (in Canada). Just make a copy of the spreadsheet and fill in your monthly expenses and it will show you the best 1 card option, 2 card option and 3 card option. Link
If people are actually using this put a message in the comments to let me know and I'll update the spreadsheet with the latest cash back rates. And if you're in another country let me know and I can try to help with a spreadsheet for your options.

In terms of sign up offers, do not take them into consideration for your long term solution. You can sign up for them and get them for short term solutions but that is a totally different story. I can write about that if you want, just let me know.