6 ways to kill your credit score

Old credit accounts count more than young ones in your credit score.

Lenders prefer borrowers who have responsibly managed the same accounts for years. That's a more reliable indicator of creditworthiness than a few months of exemplary behavior on a new account. Accounts open less than six months will hurt your score somewhat, according to Rex Johnson, founder of credit union consulting firm Lending Solutions Consulting. Those open six months or more won't, while those open at least two years will help your score.

Lenders also don't like to see a borrower who's gone on a credit binge, applying for a lot of new accounts or loans in a short period.

Every time you apply for new credit, your score may be dinged by 5 points, Johnson said. That's not the case, though, if a broker shops around for the best loans on your behalf. In that case, if they approach multiple lenders who all pull your credit report, that will only count as one inquiry so long as they all do so within a two-week window.

To boost your score: Avoid applying on your own for a lot of loans and credit cards, particularly in a short period. And avoid excessive card-hopping.