What can I do to improve my credit score?

Are you maxed out? Many scoring systems evaluate the amount of debt you have compared to your credit limits. If the amount you owe is close to your credit limit, it’s likely to have a negative effect on your score.

Have you applied for new credit lately? Many scoring systems consider whether you have applied for credit recently by looking at “inquiries” on your credit report. If you have applied for too many new accounts recently, it could have a negative effect on your score. Every inquiry isn’t counted: for example, inquiries by creditors who are monitoring your account or looking at credit reports to make “prescreened” credit offers are not considered liabilities.

Scoring models may be based on more than the information in your credit report. When you are applying for a mortgage loan, for example, the system may consider the amount of your down payment, your total debt, and your income, among other things.
Improving your score significantly is likely to take some time, but it can be done. To improve your credit score under most systems, focus on paying your bills in a timely way, paying down any outstanding balances, and staying away from new debt.

Source: Federal Trade Commission