• Pay on time: You must do whatever it takes to pay your bills on time. If you're a busy person, I recommend setting up an automatic payment so that you are sure never to pay late. If you've paid late in the past, the good news is that your most recent payment history carries more weight than past mistakes, so beginning to pay on time every time now will raise your score.
• Ask creditors to delete single sins: If your overall payment history with a company is good and you made one glaring mistake, you may be able to get the bank or credit card company to delete it. Just call up the company and ask.
• Keep ratios low: Credit scoring statistical models place a lot of weight on the ratio of how much debt you carry to how much credit you have been approved for. To improve your score, charge up no more than 30 percent of your available limit. (10 percent is even better.) If you carry balances, try to reduce them down to 30 percent.
• Move your money around: Since it's best to charge only up to 30 percent of your balance, one way to game the system a little is to move debt from one card to another. If you have one card that is near the limit and another that has little or no balance, move the debt from the former to the latter. This is no substitute for healthy payment practices, but it can give you an encouraging momentary boost.
• Request a higher limit: Another way to change your ratio of debt to credit is to tweak the credit number. You can do this by contacting your credit card companies and requesting a higher limit. In this down economy this step isn't as easy as it used to be, but the effort is worth the 15 minutes you'll spend on the phone.
• Apply for a secured credit card: If you are young with a "thin" credit file, one way to fatten it up is to sign up for a secured credit card. You put down a deposit, say $500, and in exchange, you get a credit card with a $500 limit. The activity on that card is reported to the credit bureaus, so if you handle it responsibly, you will improve your score.
• Become an authorized user: Another way to establish or improve credit is to be added as an authorized user to another person's (responsibly managed) account. Many parents do this for their kids. Even though the authorized user is not responsible for paying the bill, the account -- and all its history -- will show up on their credit report.
Here's my favorite part about raising and then maintaining your credit score: It's free! All you have to do is use your current credit responsibly and you will save thousands on your future credit. You will Save Big.