That is a secret. The Credit Scoring companies will not release the formula for determining a score. However, when a score is given, it always is accompanied by numbers or letters that relate to credit score factor explanations. Score factors are less meaningful for higher scoring credit reports as they merely point to the reasons why the person did not score even higher. Improvement of these reports is needless and trivial.
Time fixes a lot of things.
As the items age, they become less important. Correcting negative errors will improve the score, but that may take sixty to ninety days to take effect. Repeated inquires while correcting credit will worsen the score. If you are applying for a mortgage, many lenders, including Fannie Mae and Freddie Mac, have policies that a score that appears to be greatly effected by errors is to be ignored. Keep in mind that your opinion of significant may be different than that of the person approving the loan.