Your credit score is at the center of your financial universe. Creditors use your score to determine your level of risk as a borrower. If you have a poor credit score or inadequate credit history, you may only have access to the highest interest rates and terms on credit accounts. Once you've establish credit, the best way to keep your credit score up is to avoid closing your accounts. Credit Utilization Your credit utilization ratio is the amount of debt you have versus your total available credit. Generally, a 30 percent credit utilization...