An oft-cited subject of financial advice is credit cards. Cut them up. Cancel them. Have only one, for emergencies.
This isn't advice we adhere to. We use credit cards for the lion's share of our purchases. If you pay them off every month, it's like having a 25-day interest-free loan on everything you spend, all the time. For those 25 days, we're the ones earning interest on the money we spent (but not much, these days.) And Jen is a fiend for squeezing the most out of rewards programs.
This works for us because we've always been aware that spending on credit is really spending, that the bill comes due quickly, that finance charges are steep. We've never been tempted to use them to spend money we don't have.
Here I must stress that I'm not claiming this as some moral virtue. Other people can have an open package of cookies in the house and eat them one at a time. I want to eat them all. So, I don't keep packages of cookies in the house.
Temptations are a matter of temperament -- it's easy to avoid the traps in life whose bait doesn't entice you. You need to know what bait works on you. If a new credit card seems like an exciting way to get something you know you can't really afford, then maybe you should follow the "cut them up" advice.
If you know you're not tempted to spend money you don't have, and that you're good about remembering to pay your bills on time, then maybe our tack is right for you, too.
The important thing is to know yourself, and plan accordingly.
In closing, I'll note that I haven't touched on the issues of privacy or risk of identity theft in using credit cards. These issues are real, and if they've persuaded you to avoid using credit cards, I think that's a reasonable choice. Thus far, they haven't persuaded me.