while it's well known that making late payments on your mortgage or car will lower your credit score, other lesser known mistakes can also harm your rating. for example, ? has had the same credit card for the past ten years, paying the balance on time every month. she decides to get a new gold credit card so she can earn reward points and cancels her original credit card since she doesn't intend using anymore. ? is surprised to learn that her credit score is now lower. by canceling her first credit card, ? removes years of positive credit, which damaged her credit history. one day, ? receives a letter notifying her that she's been approved for a new credit card with a higher limit and lower interest than her new gold card. ? decides to transfer most of her debts to this new card and save an interest. her balance is just under the limit. however, ? credit score drops again. this is because the debt to limit ratio on her card exceeded 50%, which ? credit bureau. ? learns that it's best to keep the debt to limit ratio on her card below 30% and spread out her debt between multiple cards. ? finally pays out her credit card debt and ? by traveling for few months. when ? returns for her trip, her credit score has droped yet again. she accumulated library late fees and missed a few monthly gym payments. even these little mistakes hurt her rating.