The amount of credit cards that the person has open can affect their credit score by reducing the score by a certain number of points for each open credit card account. (discoverdebtfreedom.com)
In addition, the number credit checks that are run on you in the past year can actually reduce your score. (epic.org)
If your credit score is already low, late payments may only reduce scores by 30 points. (rebuildcreditscores.com)