The FICO credit score equation might be a black box, but there have been thousands of articles written about what you should and shouldn't do when it comes to your credit score. Most of them are pretty obvious--pay your credit card bills on time, don't apply for a lot of credit, and keep your nose clean. There are, however, a lot of weird ways you can hurt your score without you even realizing it. Closing Credit Cards. This has become less "strange" in recent years, but closing your credit cards can hurt your score. What seems like simple financial housecleaning actually affects a variety of factors that go into your credit score. When you close a card, your credit limit drops, which increases your credit utilization (bad). If that card is older than most of the other cards you have, the average age of existing accounts will also fall (bad). These are not as bad as an account in collections, but they could mean the difference between a good credit score and a bad one. Not Filling Out A Moving Form. When you move, it's often important to report your change of address to the United States Postal Service or you risk missing important mailings like credit card and utility bills. The last thing you want to do is be behind on payments because that will be reported to the credit bureaus. Some credit card companies will report you as soon as you are 30 days late. While you're at it, be sure to hold your mail when you go away. You don't want someone stealing your mail and your identity. Asking Banker to Check Score. If you have friends who work at banks, especially if they are in lending, you might be tempted to ask them to check your credit score for free. Rather than jump through the hoops of free credit score companies or paying for it yourself, it might seem harmless to ask a friend to look it up. Besides probably being misuse of company resources, this will hurt your credit score because that small favor will result in a hard inquiry on your report. When you look up your own score, the credit bureaus treat it as a soft inquiry because you are asking about yourself. When you ask your bank, all the bureau see is a bank requesting your score, as if you had applied for a loan.