Reddit user thefingolfin says:
For those who have a good handle on their spending, "use a rewards credit card instead of a debit card. I fully understand this is not a good idea for some people. I could tell you several of my friends who I would specifically recommend to not use a credit card. However, in my situation, where I have great mutual accountability between me and my wife, the $300 sign-up bonus and the one to five percent cash back on purchases has been a nice source of extra money and hasn't increased our spending at all."