Pay your bills on time. Delinquent payments and collections can have a major negative impact on your score. If you have missed payments, get current and stay current. The longer you pay your bills on time, the better your score. Be aware that paying off a collection account will not remove it from your credit report. It will stay on your report for seven years.

Keep balances low on credit cards and other “revolving credit"; high outstanding debt can affect a score. The most effective way to improve your score in this area is by paying down your revolving credit, not closing accounts and spreading debt among fewer accounts. Owing the same amount but having fewer open accounts may lower your score; however splitting moderate debt between two cards instead of piling it on one card can sometimes be a good strategy.

Don't close unused credit cards as a short-term strategy to raise your score, and don't open a number of new credit cards that you don't need, just to try to increase your available credit. This approach could backfire and lower your score.

A limited credit history can have a negative effect. Someone with no credit cards tends to appear as a higher risk than someone who has managed credit cards responsibly. If you don’t have a credit history, consider opening an account at a bank and using it responsibly, making the monthly payments as required, but don't open a lot of new accounts too quickly. New accounts will lower your average account age, which will have a larger effect on your score if you don't have a lot of other credit information. Also, rapid account buildup can look risky if you are a new credit user.

Apply for and open new credit accounts only as needed. Don't open accounts just to have a better credit mix - it won't raise your score. In general, having credit cards and installment loans (and paying timely payments) will raise your score. Note that closing an account doesn't make it go away. A closed account will still show up on your credit report and may show the payment history, although it will be noted as closed and paid.

Do your rate shopping for a single loan within a focused period of time. FICO scores distinguish between a search for a single loan and a search for many new credit lines in part by the length of time over which inquiries occur. Note that it's OK to request and check your own credit report. This won't affect your score as long as you order your credit report directly from the credit reporting agency or through an organization authorized to provide credit reports to consumers.

If you are having trouble making ends meet, contact your creditors or see a legitimate credit counselor. This won't improve your score immediately, but if you can begin to manage your credit and pay on time, your score will get better over time. Re-establish your credit history if you have had problems. Opening new accounts responsibly and paying them off on time will raise your score in the long term.

On average, lenders like to see three to four open accounts -- a combination of charge cards, auto loans, etc. Limit department store cards and other store cards and finance company loans as those may lower your rating.