It's pretty safe to say that America runs on credit. According to the Federal Reserve, the aggregate amount of credit card debt recently surpassed $1 trillion, joining the ranks of auto loans and student loan debt as topping the $1 trillion mark. America runs on credit Furthermore, roughly seven in 10 Americans had at least one credit card as of 2015, with the average card-carrying American toting around 3.7 credit cards, according to CreditCards.com. And it's not just a single generation that's flocked to credit cards. Two out of every three young millennials (ages 18 to 24) carries a credit card, while roughly three out of four folks in Generation X and the baby boomer generation have a card. Image source: Getty Images. Why the reliance on credit? Part of the answer could be a poor understanding of cash flow and the financial need to lean on credit. After all, Gallup found in 2013 that only 32% of American households kept a detailed monthly budget. There are probably quite a few individuals and families that aren't managing their money wisely and are thus forced to turn to credit to fuel their consumption. However, another very probable reason Americans turn to credit cards and other forms of loans is to build up their credit history. While most people are probably aware that a good credit score can help you get a home loan and a decent interest rate, they may be unaware that their credit report can have other impacts on their life. For instance, a future employer can request to see your credit report, as can a prospective landlord, with the quality of your credit history factoring into whether you get the job or home of your dreams. Even utility and insurance companies can check your credit report to determine your deposit (for utilities) or monthly rate (for insurers). Here's how much a poor credit score can cost you As you might have expected, having a low credit score can certainly affect your ability to get a home loan, open a credit card, or receive an attractive interest rate. Just how badly can a poor credit score affect you? Let's turn to a recent report from ValuePenguin for answers. Image source: Getty Images. ValuePenguin reviewed more than 100 credit cards to determine just how much of a variance consumers with poor creditworthiness dealt with compared with those with high creditworthiness. The results showed that those with poor credit score pay, on average, 80% more to pay off their credit card debt than those with good or excellent credit scores. People with low credit scores may also need up to 26 extra months to pay off their balance relative to good-credit folks, based on a $2,500 starting balance and the assumption that minimum payments are being made. Within their sampling, ValuePenguin even found instances where those with low credit scores paid double in interest what those with good credit scores paid, as a result of wide ranges in credit card APRs between poor and good credit scores. A prime example used is the JetBlue Card. Assuming a person had $15,000 in debt and made 8% monthly payments, the good-credit customer would pay $2,071 in interest before the debt disappeared, compared with $4,859 in interest for the poor-credit customer. While there's no precise formula for determining which credit cards punish those with poor credit scores the most, certain types of credit cards clearly had higher average APR ranges based on ValuePenguin's analysis. Arguably the most alluring credit card, the cash-back reward card, had the widest variable APR range of 13.24% on the low end and 22.99% on the high end. That's a 9.75-percentage-point spread, and it could wind up eating those with low credit scores alive if they regularly carry a monthly balance. Student credit cards and airline credit cards also had notoriously high spreads of 8.63 percentage points and 7.37 percentage points, respectively, based on ValuePenguin's findings. Conversely, travel credit cards offered the smallest spread of just 3.62 percentage points. Image source: Getty Images. What's a person with a low credit score to do? So, what should you do if your credit score is less than perfect? While raising the white flag might be easy, it's not the most prudent decision. Here's a to-the-point list of ways you can improve your situation. Be smart about opening new accounts: Your options may be limited when opening a new credit account if you have a low credit score, but you should still do your homework and aim for credit cards that offer more favorable rates for low-credit consumers. Though this can be difficult to do because you won't know your APR till you're approved, there are resources that can easily allow you to compare credit cards for those with bad credit scores. Request an interest-rate reduction: Somewhere in the neighborhood of three out of four cardholders who ask for their interest rate to be reduced are successful. That's because it costs lenders far more to market to new customers than to hang on to existing customers, so they often have an incentive to work with you. The issue is that so few cardholders actually call their lender and request a rate reduction, because they believe they'll be told "no." If you have a recent history of timely payments and prudent credit usage, you may indeed have a case for an APR reduction. Consider a balance-transfer card: Another smart option to consider, as ValuePenguin noted, is a balance-transfer credit card. These cards commonly offer introductory APRs of 0% for 12 to 15 months, allowing a cardholder to really make headway on his or her balance. Even with a potential 3% to 5% transfer fee, it's often well worth consolidating debt on a balance-transfer card. Be mindful of your credit basics: Finally, continue to work on improving your credit score, as it'll give you more leverage when negotiating with credit card companies. Practically two-thirds of your credit score is determined by making timely payments and keeping your total credit utilization below 30%, so this should be your primary focus. In addition, keep good-standing accounts open, avoid opening credit accounts for unnecessary reasons, and try to keep a good mix of revolving and installment accounts. Having a poor credit score isn't optimal, but it can always be improved. Being proactive can go a long way toward righting the ship and lowering what you'll pay in out-of-pocket interest expenses. 5 Simple Tips to Skyrocket Your Credit Score Over 800!Increasing your credit score above 800 will put you in rare company. So rare that only 1 in 9 Americans can claim they're members of this elite club. But contrary to popular belief, racking up a high credit score is a lot easier than you may have imagined following 5 simple, disciplined strategies. You'll find a full rundown of each inside our FREE credit score guide. It's time to put your financial future first and secure a lifetime of savings by increasing your credit score. Simply click here to claim a copy 5 Simple Tips to Skyrocket Your Credit Score over 800.Sean Williams has no position in any of the stocks mentioned. The Motley Fool recommends JetBlue Airways. The Motley Fool has a disclosure policy.