Have a credit card or two? No problem - but how you’re managing them might be, especially when you consider how much common blunders can cost. Whether you’re looking to build your credit, earn points or avoid carrying cash, credit cards have plenty of perks. They also have expensive pitfalls. Here we’ll take a look at how much a few common credit card mistakes cost and how you can play your cards right to save...• Mistake #1: Paying the minimumIf you pay for something with a credit card, that purchase is interest free – if you pay it off in full the due date. Otherwise, you’ll be paying interest. That isn’t the worst thing if it happens occasionally, but maintaining a credit card balance is an expensive habit to get into. How expensive? Let’s say you have a typical credit card with a 19.99 percent interest rate and you rack up $500 (fairly easy, right?). The minimum monthly payment on this charge is going to be somewhere around $10 (or 2 percent of your balance). This means that you’ll pay about $8 of interest per month. (That’s in the first year of your $500 repayment plan, and it assumes that you don’t rack up your balance any higher.) Here’s where things get ugly... at this rate, it’ll take you more than nine years to pay off the balance and cost you more than $500 in interest (more than double your original balance).The solution? You’d better at least make the minimum payment to avoid putting a dent in your credit score, says Stephen Menon, associate vice president of credit cards at TD Canada Trust. And if you don’t pay the balance off in full, make sure you at least understand what you’re in for so that you can incorporate that cost into your budget. Better still, only put on credit what you can afford to immediately pay off before interest charges kick in. • Mistake #2: Missing a monthly paymentAccording to a recent poll TD, 23 percent of respondents between the ages of 18 and 35 had missed a monthly credit card payment – a very costly error. Not only does your debt continue to grow thanks to the high interest, but you may also incur an administrative fee. Miss a few payments and it’ll start to show on your credit score, which will make it harder and more expensive for you to borrow down the road.The solution? Don’t miss a single payment! Menon says there’s no penalty charge for late payments in Canada. That’s good news, but if you manage to ding your credit score, you’ll be paying for this mistake for many years to come.• Mistake #3: Using a credit card to supplement your incomeListen carefully: Your credit card is no substitute for cash. Sure, it’ll work in a pinch, but if you’re routinely using it to finance your groceries and gas, well, Houston, we have a problem, and it’s one that could result in a major personal financial crash. The solution? Work on coming up with a budget based on what you earn, rather than relying on a credit card to make ends meet. • Mistake #4: Maxing out your cardWhether you have an appetite for luxury or just hate doing the math, it doesn’t take much effort to max out a credit card. Unfortunately, this is one mistake that’ll really make a dent because having a high amount of credit card debt can greatly impact your bottom line. Let’s say you have a credit card with a $5,000 limit. That’s not uncommon, but neither are limits of $10,000 or more. If you rack up this card, you’ll have to make minimum payments of at least $100 per month, most of which will be interest, and paying off the balance will be an uphill battle. Routinely going over the max can also have repercussions for your credit score. The solution? Thanks to new credit card rules introduced in Canada in 2010, credit card issuers can’t raise your credit card limit unless you ask them to, so make sure you do so if you’re planning to make a big purchase. Just make sure it’s something you can afford to pay off, okay? How to play the game rightMany people blame credit cards for putting their financial futures on the line. The truth is, they’re only as dangerous as the person holding them. So play your cards right finding a credit card that meets your needs, learn about the costs it can incur and avoid expensive mistakes. You really can get to enjoy all of a credit card’s benefits - without ending up with a losing hand.