This number can stand between you and a new home, car, or loan. Ranging from 300 to 850 and called a FICO score, it helps lenders assess your risk of default, explains Liz Pulliam Weston, author of Your Credit Score (Prentice Hall, www.amazon.com$18). Generally, 720 and above is considered good, from 620 to 720 is mediocre, and less than 620 is poor. “One bank may grant credit only to people with scores over 725, while another may be happy with a 680,” says David Rubinger, vice president of the credit reporting agency Equifax. Thanks to a new federal law, annual credit reports will be available at no cost in all states by September 1 (and are already free for those in the West and Midwest). To get yours, or to find out when it will be free in your area, go to www.annualcreditreport.com. If it’s not free yet, you can still get a no-cost estimated FICO through Bankrate, at www.bankrate.com. Finally, keep your credit balances low and pay bills on time. “One missed payment,” Weston warns, “can knock 100 points off your score.”