No. 6: Medical debt is treated differently on credit reports

Credit bureaus do not discriminate when it comes to medical payments. Typically, medical bills are not reported to a bureau unless the bills are sent to a collection agency. When that happens, "medical collections are the same as any other collections," Detweiler says. "They are a serious negative. The more recent they are, the more it affects your score."

No. 7: A credit repair company can only remove inaccuracies to improve my score

While it's true credit repair companies help you get inaccurate information corrected on your credit report, they can sometimes go one step further. "The real core competency of a credit repair company is to get stuff that's negative removed from your credit report – whether it's accurate or inaccurate," Ulzheimer says.

No. 8: So that means a credit repair company takes illegal action to fix my score

No, what they do is perfectly legal as long as they follow a federal statute called the Credit Repair Organizations Act. Every state has its own version of CROA. "It is a law filled with teeth," Ulzheimer says. For one, companies must disclose that they're going to take actions you could technically do yourself (at no cost), and they can't charge you until after the services have been rendered. They also can't guarantee anything, Ulzheimer says. "If they say, 'I can have that bankruptcy deleted, guaranteed,' that's a violation of the Credit Repair Organizations Act."

No. 9: My utilization rate doesn't matter

Utilization is an important measurement in the credit scoring system. "It can wildly change your score in a short period of time in either direction," Ulzheimer says. He explains it as the percentage of the credit cards you're using at any given time. To calculate your utilization percentage, divide your credit card balances by your total credit card limits and multiply by 100. "The higher that percentage, the fewer points you're going to earn in that particular category, depending on the scoring system," Ulzheimer says. "The lower the percentage, the better it will be for your score." The credit score tracking website CreditKarma.com recommends that consumers shouldn't exceed 30 percent.

No. 10: I should avoid new store credit cards because they'll hurt my score

You've likely been asked at checkout: "Would you like to open a store credit card and receive 20 percent off your purchase today?" For some consumers, it's a good idea to say yes. "That's a great way for many people who might not qualify for other kinds of cards to get a credit card," Sweet says. A store credit card can help raise your credit limit, improve your utilization rate and boost your overall score. Of course, you shouldn't sign up if you'll be tempted to use the card every day, Sweet says, "but don't just automatically assume it's a bad thing before you open that account."

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