Banks make their easiest profits not from traditional lending but from nuisance fees, past-due charges and other extra costs paid by consumers.
Most are avoidable with a little vigilance. Declaring war on random fees can pay for a nice restaurant dinner.
Bounced-check charges are almost pure gravy for banks, far surpassing banks' cost to process overdrafts. You should fanatically avoid bouncing checks.
Checking-account fees are almost obsolete. Many banks offer "totally free" checking that lives up to its name. Make sure your bank doesn't charge extra if you pay for a safe-deposit box or other services with a check instead of a direct draft.
Use automated teller machines bearing your bank's label to avoid withdrawal charges. Make sure the bank isn't dinging you for too many customer-service calls.
Credit cards are a deep well of nuisance fees. You know about the interest rates - approaching 20 percent in many cases even as banks' short-term cost of borrowing money is near zero.
What's easier to miss are the charges that pile on top if you're not on guard. Miss a monthly card payment and you may wind up paying not just a late fee but also a higher interest rate on your balance.
Going over your credit limit can also trip the hair-trigger fee machine. So can requesting a higher balance limit. So can transferring a balance from another card.
Unless your credit-rating is quite poor, there's really no reason to pay an annual maintenance fee on a card, either.
And never get cash advances or use the "convenient" checks credit-card companies send every so often. They often come with fees that would not have applied had you spent the same money with your card.