A credit card is a tool. Like most tools, it is useful when used correctly and destructive when used carelessly. I have used credit cards for years, collected rewards, and never paid a dollar of interest. My credit score has always been in the 800s. The difference between someone who benefits from credit cards and someone who gets wrecked by them comes down to a few simple behaviors.
The interest rate is designed to be a trap
Credit card interest rates are some of the highest legal rates charged to consumers. Even people with excellent credit often face rates of 20% or higher on their balances, because credit card debt is unsecured. The card company has no collateral, meaning there is nothing for them to take from you if you don't make your payments. This is different than an auto loan in which the bank holds the title to the asset (the car) until the loan is paid in full. They charge accordingly.
The business model of credit card companies depends on you carrying a balance. When you pay only the minimum, they earn interest on everything else. They make it easy to do this by setting minimum payments low enough that you barely notice. Meanwhile, the balance barely moves and interest accrues every month.
Minimum payments vs. paying in full — $3,000 balance at 24% APR
Paying minimum (~$60/mo)6+ years to pay off, $2,700+ in interest
Paying $150/mo~2 years, ~$600 in interest
Paying in full each month$0 in interest
Two rules that prevent almost every credit card problem
Set up autopay for the full balance. Not the minimum. The full statement balance, every month, automatically. This removes the possibility of forgetting a payment, missing the due date, or making an impulse decision to only pay the minimum. The bill comes, autopay pays it, you owe nothing.
Turn on notifications. Every transaction should trigger a notification to your phone. This keeps you aware of what is being charged to your account, catches fraud early, and gives you a real-time sense of where your spending is going without needing to check an app.
I had autopay set up on a store card when the underlying bank switched processors. The transition canceled my autopay without notifying me. I paid interest for the first and only time in my life and had to fight to get it reversed. Even with autopay, monitor your accounts. The system can break without warning.
Only use cards when they benefit you
Every dollar you put on a rewards card earns points, miles, or cash back. My AMEX Gold earns meaningful rewards on dining and groceries. My Amazon card returns 5% on Amazon purchases, which adds up given how often I use it. These are real dollars back in my pocket for spending I would have done anyway.
The rewards only make sense if you pay in full every month. The moment you carry a balance, the interest cost wipes out whatever you earned in rewards and then some. A 2% cash back card charging you 24% in interest is not a good deal.
Keep requesting limit increases
As your income grows, request credit limit increases on your existing cards. Most issuers will approve this once a year or so if you ask. A higher limit with the same spending level means lower utilization, which helps your credit score. It is not an invitation to spend more. It is a score management tool.
The takeaway
Use credit cards for the rewards and the credit building. Set autopay to the full balance and turn on transaction notifications. Never carry a balance. Request limit increases as your income grows. Follow these rules and you will never pay interest, your score will stay high, and the card will be working for you instead of against you.