To learn what affects your personal scores, get a list of the risk factor statements for the score you received. Those factors are provided with most credit scores you purchase.
The risk factors describe what had the most negative impact on your credit score. By comparing those factors to your credit report, you can begin to take steps to change your credit management behavior over time, which will result in improved credit scores.
While the numbers can be quite different from one credit score model to another, risk factors tend to be very consistent. So, addressing the risk factors from one score will help you improve all credit scores calculated using your credit report.
Making payments on time and in full is the best way to keep your risk level low. Mistakes you have made in the past will have less of an impact as they become more distant.
A number of companies promise quick and easy fixes for credit problems. They often talk about credit repair and the ability to erase negative information from your file. However, there is no way to permanently remove negative information, unless it is inaccurate.
The FTC has information on credit repair: http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre13.shtm
The three national credit bureaus: