Credit scores range between 200 and 850, with scores above 620 considered desirable for obtaining a mortgage. The following factors affect your score:

Your payment history.

Did you pay your credit card bills on time? Bankruptcy filing, liens, and collection activity also affect your history.

How much you owe and where. 

If you owe a great deal of money on numerous accounts, it can indicate that you are overextended. However, spreading debt among several accounts can help you avoid approaching the maximum on any individual credit line.

The length of your credit history.

In general, the longer an account has been open, the better.

How much new credit you have.

New credit—whether in the form of installment plans or new credit cards—is considered more risky, even if you pay down the debt promptly.

The types of credit you use.

Generally, it’s desirable to have more than one type of credit—such as installment loans, credit cards, and a mortgage.